Deflection rod system for a dynamic stabilization and motion preservation spinal implantation system and method

ABSTRACT

A dynamic stabilization, motion preservation spinal implant system includes an anchor system, a horizontal rod system and a vertical rod system. The systems are modular so that various constructs and configurations can be created and customized to a patient.

CLAIM TO PRIORITY

This application claims priority to all of the following applicationsincluding U.S. Provisional Application No. 60/942,162, filed Jun. 5,2007, entitled “Dynamic Stabilization and Motion Preservation SpinalImplantation System and Method” (Attorney Docket No. SPART-01010US0),

U.S. patent application Ser. No. 11/832,260, filed Aug. 1, 2007,entitled “Shaped Horizontal Rod for Dynamic Stabilization and MotionPreservation Spinal Implantation System and Method” (Attorney Docket No.SPART-01006US0),

U.S. patent application Ser. No. 11/832,273, filed Aug. 1, 2007,entitled “Multi-directional Deflection Profile for a DynamicStabilization and Motion Preservation Spinal Implantation System andMethod” (Attorney Docket No. SPART-01007US0),

U.S. patent application Ser. No. 11/832,305, filed Aug. 1, 2007,entitled “A Horizontal Rod with a Mounting Platform for a DynamicStabilization and Motion Preservation Spinal Implant System and Method”(Attorney Docket No. SPART-01008US0),

U.S. patent application Ser. No. 11/832,330, filed Aug. 1, 2007,entitled “Multi-dimensional Horizontal Rod for a Dynamic Stabilizationand Motion Preservation Spinal Implantation System and Method” (AttorneyDocket No. SPART-01009US0),

U.S. patent application Ser. No. 11/832,338, filed Aug. 1, 2007,entitled “A Bone Anchor With a Yoke-Shaped anchor head for a DynamicStabilization and Motion Preservation Spinal Implantation System andMethod” (Attorney Docket No. SPART-01010US1),

U.S. patent application Ser. No. 11/832,358, filed Aug. 1, 2007,entitled “A Bone Anchor With a Curved Mounting Element for a DynamicStabilization and Motion Preservation Spinal Implantation System andMethod” (Attorney Docket No. SPART-01011US0),

U.S. patent application Ser. No. 11/832,377, filed Aug. 1, 2007,entitled “Reinforced Bone Anchor for a Dynamic Stabilization and MotionPreservation Spinal Implantation System and Method” (Attorney Docket No.SPART-01012US0),

U.S. patent application Ser. No. 11/832,400, filed Aug. 1, 2007,entitled “A Bone Anchor With a Compressor Element for Receiving a Rodfor a Dynamic Stabilization and Motion Preservation Spinal ImplantationSystem and Method” (Attorney Docket No. SPART-01013US0),

U.S. patent application Ser. No. 11/832,413, filed Aug. 1, 2007,entitled “Dynamic Stabilization and Motion Preservation SpinalImplantation System and Method with a Deflection Rod” (Attorney DocketNo. SPART-01014US0),

U.S. patent application Ser. No. 11/832,426, filed Aug. 1, 2007,entitled “Dynamic Stabilization and Motion Preservation SpinalImplantation System and Method with a Deflection Rod Mounted in CloseProximity to a Mounting Rod” (Attorney Docket No. SPART-01015US0),

U.S. patent application Ser. No. 11/832,436, filed Aug. 1, 2007,entitled “Dynamic Stabilization and Motion Preservation SpinalImplantation System and Method” (Attorney Docket No. SPART-01016US0),

U.S. patent application Ser. No. 11/832,446, filed Aug. 1, 2007,entitled “Super-Elastic Deflection Rod for a Dynamic Stabilization andMotion Preservation Spinal Implantation System and Method” (AttorneyDocket No. SPART-01017US0),

U.S. patent application Ser. No. 11/832,470, filed Aug. 1, 2007,entitled “Revision System and Method for a Dynamic Stabilization andMotion Preservation Spinal Implantation System and Method” (AttorneyDocket No. SPART-01020US0),

U.S. patent application Ser. No. 11/832,485, filed Aug. 1, 2007,entitled “Revision System for a Dynamic Stabilization and MotionPreservation Spinal Implantation System and Method” (Attorney Docket No.SPART-01021US0),

U.S. patent application Ser. No. 11/832,494, filed Aug. 1, 2007,entitled “Dynamic Stabilization and Motion Preservation SpinalImplantation System and Method” (Attorney Docket No. SPART-01022US0),

U.S. patent application Ser. No. 11/832,517, filed Aug. 1, 2007,entitled “Implantation Method for Dynamic Stabilization and MotionPreservation Spinal Implantation System and Method” (Attorney Docket No.SPART-01023US0),

U.S. patent application Ser. No. 11/832,527, filed Aug. 1, 2007,entitled “Modular Spine Treatment Kit for Dynamic Stabilization andMotion Preservation of the Spine” (Attorney Docket No. SPART-01024US0),

U.S. patent application Ser. No. 11/832,534, filed Aug. 1, 2007,entitled “Horizontally Loaded Dynamic Stabilization and MotionPreservation Spinal Implantation System and Method” (Attorney Docket No.SPART-01025US0),

U.S. patent application Ser. No. 11/832,548, filed Aug. 1, 2007,entitled “Dynamic Stabilization and Motion Preservation SpinalImplantation System with Horizontal Deflection Rod and ArticulatingVertical Rods” (Attorney Docket No. SPART-01029US0),

U.S. patent application Ser. No. 11/832,557, filed Aug. 1, 2007,entitled “An Anchor System for a Spine Implantation System That Can MoveAbout three Axes” (Attorney Docket No. SPART-01030US0,

U.S. patent application Ser. No. 11/832,562, filed Aug. 1, 2007,entitled “Rod Capture Mechanism for Dynamic Stabilization and MotionPreservation Spinal Implantation System and Method” (Attorney Docket No.SPART-01031US0),

U.S. Provisional Application No. 61/028,792, filed Feb. 14, 2008,entitled “A Deflection Rod System for a Dynamic Stabilization and MotionPreservation Spinal Implantation System and Method” (Attorney Docket No.SPART-01035US0),

U.S. Provisional Application 61/031,598, filed Feb. 26, 2008, entitled“A Deflection Rod System for a Dynamic Stabilization and MotionPreservation Spinal Implantation System and Method” (Attorney Docket No.SPART-01037US0), and

U.S. Provisional Application No. 61/______, filed May ______, 2008,entitled “A Spine Implant With A Deflection Rod System Aligned With ABone Anchor And Method” (Attorney Docket No.: SPART-01039US0).

All of the afore-mentioned applications are incorporated herein byreference in their entireties.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to all of the following applicationsincluding U.S. patent application Ser. No. 12/______, filed May ______,2008, entitled “A Deflection Rod System For A Spine Implant Including AnInner Rod And An Outer Shell And Method” (Attorney Docket No.:SPART-01035US1);

U.S. patent application Ser. No. 12/______, filed May ______, 2008,entitled “A Deflection Rod System With A Deflection Contouring ShieldFor A Spine Implant And Method” (Attorney Docket No.: SPART-01035US2);

U.S. patent application Ser. No. 12/______, filed May ______, 2008,entitled “Dynamic Stabilization And Motion Preservation SpinalImplantation System With A Shielded Deflection Rod System And Method”(Attorney Docket No.: SPART-01035US3);

U.S. patent application Ser. No. 12/______, filed May ______, 2008,entitled “A Deflection Rod System For Spine Implant With End ConnectorsAnd Method” (Attorney Docket No.: SPART-01035US4);

U.S. patent application Ser. No. 12/______, filed May ______, 2008,entitled “A Deflection Rod System For A Dynamic Stabilization And MotionPreservation Spinal Implantation System And Method” (Attorney DocketNo.: SPART-01035US5);

U.S. patent application Ser. No. 12/______, filed May ______, 2008,entitled “A Deflection Rod System With Mount For Dynamic StabilizationAnd Motion Preservation Spinal Implantation System And Method” (AttorneyDocket No.: SPART-01037US1);

U.S. patent application Ser. No. 12/______, filed May ______, 2008,entitled “A Deflection Rod System With Mount For Dynamic StabilizationAnd Motion Preservation Spinal Implantation System And Method” (AttorneyDocket No.: SPART-01037US2);

U.S. patent application Ser. No. 12/______, filed May ______, 2008,entitled “A Deflection Rod System With A Non-Linear Deflection To LoadCharacteristic For Dynamic Stabilization And Motion Preservation SpinalImplantation System And Method” (Attorney Docket No.: SPART-01037US3);

U.S. patent application Ser. No. 12/______, filed May ______, 2008,entitled “A Deflection Rod System Dimensioned For Deflection To A LoadCharacteristic For Dynamic Stabilization And Motion Preservation SpinalImplantation System And Method” (Attorney Docket No.: SPART-01037US4);

U.S. patent application Ser. No. 12/______, filed May ______, 2008,entitled “A Deflection Rod System For Use With A Vertebral FusionImplant For Dynamic Stabilization And Motion Preservation SpinalImplantation System And Method” (Attorney Docket No.: SPART-01037US5);

U.S. patent application Ser. No. 12/______, filed May ______, 2008,entitled “A Dual Deflection Rod System For Dynamic Stabilization AndMotion Preservation Spinal Implantation System And Method” (AttorneyDocket No.: SPART-01037US6);

U.S. patent application Ser. No. 12/______, filed May ______, 2008,entitled “Method For Implanting A Deflection Rod System And CustomizingThe Deflection Rod System For A Particular Patient Need For DynamicStabilization And Motion Preservation Spinal Implantation System”(Attorney Docket No.: SPART-01037US7);

U.S. patent application Ser. No. 12/______, filed ______, 2008, entitled“A Spine Implant With A Deflection Rod System Anchored To A Bone AnchorAnd Method” (Attorney Docket No.: SPART-01039US1);

U.S. patent application Ser. No. 12/______, filed ______, 2008, entitled“A Spine Implant With A Deflection Rod System Including A DeflectionLimiting Shield Associated With A Bone Screw And Method” (AttorneyDocket No.: SPART-01039US2);

U.S. patent application Ser. No. 12/______, filed ______, 2008, entitled“A Spine Implant With A Dual Deflection Rod System Including ADeflection Limiting Shield Associated With A Bone Screw And Method”(Attorney Docket No.: SPART-01039US4);

U.S. patent application Ser. No. 12/______, filed ______, 2008, entitled“A Spine Implant With A Deflection Rod System And Connecting LinkagesAnd Method” (Attorney Docket No.: SPART-01039US7); and

U.S. patent application Ser. No. 12/______, filed ______, 2008, entitled“A Spine Implant With A Deflection Rod System Aligned With A Bone AnchorAnd Method” (Attorney Docket No.: SPART-01039US8).

All of the afore-mentioned applications are incorporated herein byreference in their entireties.

BACKGROUND OF INVENTION

The most dynamic segment of orthopedic and neurosurgical medicalpractice over the past decade has been spinal devices designed to fusethe spine to treat a broad range of degenerative spinal disorders. Backpain is a significant clinical problem and the annual costs to treat it,both surgical and medical, is estimated to be over $2 billion. Motionpreserving devices to treat back and extremity pain has, however,created a treatment alternative to or in combination with fusion fordegenerative disc disease. These devices offer the possibility ofeliminating the long term clinical consequences of fusing the spine thatis associated with accelerated degenerative changes at adjacent disclevels.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an embodiment of a dynamic spinestabilization system of the invention.

FIG. 1A is a posterior view of the embodiment of FIG. 1 implanted in aspine.

FIG. 2 is a top view of the embodiment of FIG. 1.

FIG. 3 is a perspective view of an embodiment of a horizontal rod systemof the invention for use with a dynamic spine stabilization system suchas depicted in FIG. 1.

FIG. 4 is a perspective view of an alternative embodiment of ahorizontal rod system of the invention for use with a dynamic spinestabilization system such as depicted in FIG. 1.

FIG. 5 is a perspective view of an embodiment of an anchor system of theinvention for use with a dynamic spine stabilization system such asdepicted in FIG. 1.

FIG. 6 is another perspective view of the embodiment of the anchorsystem of FIG. 5.

FIG. 7 is an exploded perspective view of an alternative embodiment ofthe anchor system of the invention for use with a dynamic spinestabilization system such as depicted in FIG. 1.

FIG. 8 is a sectioned view of a portion of embodiment of the alternativeanchor system of FIG. 7 of the invention.

FIG. 9 is a side view of the anchor system of FIG. 7 depicting a degreeof freedom of movement of the anchor system of FIG. 7.

FIG. 9A is an end view of the anchor system of FIG. 9.

FIG. 10 is a side view of the anchor system of FIG. 7 depicting anotherdegree of freedom of movement of the anchor system of FIG. 7.

FIG. 10A is an end view of the anchor system of FIG. 10.

FIG. 11 is a side view of the anchor system of FIG. 7 depicting yetanother degree of freedom of movement of the anchor system of FIG. 7.

FIG. 12 is a perspective view of yet another embodiment of the anchorsystem of the invention.

FIG. 13 is an exploded perspective view of the embodiment of the anchorsystem of the invention of FIG. 12.

FIG. 14 is a perspective view of yet another embodiment of the anchorsystem of the invention.

FIG. 15 is an exploded perspective view of the embodiment of the anchorsystem of the invention of FIG. 14.

FIG. 16 is another exploded perspective view of the embodiment of theanchor system of the invention of FIG. 14.

FIG. 17 is an exploded perspective view of another embodiment of theanchor system of the invention.

FIG. 18 is a perspective view of yet another embodiment of the anchorsystem of the invention.

FIG. 19 is a perspective view of another embodiment of a dynamic spinestabilization system of the invention with another horizontal rodsystem.

FIG. 19A is a perspective view of another horizontal rod system of theinvention as depicted in FIG. 19 and partially shown in phantom form.

FIG. 19B is an exploded perspective view of the embodiment of FIG. 19.

FIG. 19C is a side view of the embodiment of FIG. 19.

FIG. 20 is a top view of another embodiment of the dynamic spinestabilization of the system of the invention of FIG. 19.

FIG. 20A is a top side of the embodiment depicted in FIG. 19A.

FIG. 21 is another perspective view of the embodiment of the dynamicspine stabilization of the invention of FIG. 19.

FIG. 22 is a side view the embodiment of the horizontal rod system ofthe invention as depicted in FIG. 19 configured in a closed position forimplantation.

FIG. 22A is an end view of the embodiment depicted in FIG. 22.

FIG. 23 is a side view partially in phantom form of the horizontal rodsystem of FIG. 22.

FIG. 24 is a side view of the embodiment of FIG. 22 in an open positionas used when the embodiment is deployed in a spine.

FIG. 25 is an end view of the embodiment depicted in FIG. 24.

FIG. 26 is a perspective view of yet another embodiment of thehorizontal rod system of the invention.

FIG. 27 is a side view of the embodiment of the horizontal rod system ofthe invention of FIG. 26.

FIG. 28 is a perspective view of still another embodiment of thehorizontal rod system of the invention.

FIG. 29 is a side view of the embodiment of the horizontal rod system ofthe invention of FIG. 28.

FIG. 30 is a top view of another embodiment of the horizontal rod systemof the invention as depicted in FIG. 1 with the horizontal rod system inan undeployed position ready for implantation.

FIG. 31 is a top view of the embodiment of the horizontal rod system ofFIG. 30 in a deployed position after implantation.

FIG. 32 is a side view, partially in phantom of the embodiment depictedin FIG. 30.

FIG. 33 is a side view of an alternative embodiment of the horizontalrod system of the invention.

FIG. 33A is a side view of yet another embodiment of the horizontal rodsystem of the invention.

FIG. 34 is a side view of another alternative embodiment of thehorizontal rod system of the invention.

FIG. 34A is a perspective view of yet another embodiment of thehorizontal rod system of the invention.

FIG. 34B is a side view of the embodiment of FIG. 34A.

FIG. 34C is a top view of the embodiment of FIG. 34A.

FIG. 35 is a side view of still another alternative embodiment of thehorizontal rod system of the invention.

FIG. 36 is a side view of yet another alternative embodiment of thehorizontal rod system of the invention.

FIG. 37 is a side view of another alternative embodiment of thehorizontal rod system of the invention.

FIG. 38 is a side view of another alternative embodiment of thehorizontal rod system of the invention.

FIG. 39 is a side view of yet another alternative embodiment of thehorizontal rod system of the invention.

FIG. 39A is still another embodiment of the horizontal rod system andthe anchor system of the invention.

FIG. 39B is yet another embodiment of the horizontal rod system and theanchor system of the invention.

FIG. 40 is a perspective view of another embodiment of a dynamic spinestabilization system of the invention.

FIG. 41 is a perspective view of still another embodiment of a dynamicspine stabilization system of the invention.

FIG. 42 is a side view of an embodiment of a two level dynamic spinestabilization system of the invention.

FIG. 43 is a side view of yet another embodiment of a two level dynamicspine stabilization system of the invention.

FIG. 43A is a side view of an alternative embodiment of a dynamic spinestabilization system of the invention.

FIG. 44 is a side view of an embodiment of a fusion system of theinvention.

FIG. 45 is a side view of an embodiment of a two level fusion system ofthe invention.

FIGS. 45A, 45B are perspective and side views of still another fusionsystem of an embodiment of the invention that has a transition level.

FIG. 46 is a flow chart of an embodiment of the method of the invention.

FIG. 47 is yet another embodiment of the horizontal rod system of theinvention.

FIG. 48 is a perspective view of an embodiment of a dynamic spinestabilization system of the invention.

FIG. 49 is a posterior view of an embodiment of a dynamic spinestabilization system of the invention.

FIG. 50A is a perspective view of an embodiment of the horizontal rodsystem and a connector of the invention.

FIG. 50B is a perspective view of an embodiment of a horizontal rodsystem, a vertical rod system and a connector of the invention.

FIG. 51 is a perspective view of an embodiment of a horizontal rodsystem, a vertical rod system and a connector of the invention.

FIG. 52 is a perspective view of an embodiment of a horizontal rodsystem, a vertical rod system and a connector of the invention.

FIG. 53 is a perspective view of an embodiment of a horizontal rodsystem, a vertical rod system and a connector of the invention.

FIG. 54 is a sectional view of an embodiment of a horizontal rod system,a vertical rod system and a connector of the invention.

FIG. 55A is a sectional view of an embodiment of a horizontal rodsystem, a vertical rod system and a connector of the invention.

FIG. 55B is a sectional view of an embodiment of a horizontal rodsystem, a vertical rod system and a connector of the invention.

FIG. 56A is a front view of an embodiment of a horizontal rod system, avertical rod system and a connector of the invention.

FIG. 56B is a front view of an embodiment of a horizontal rod system, avertical rod system and a connector of the invention.

FIG. 57 is a perspective view of an embodiment of a vertical rod systemof the invention.

FIG. 58 is a perspective view of an embodiment of a lock tab of aconnector of the invention.

FIG. 59 is a sectional view of an embodiment of a vertical rod systemand a connector of the invention.

FIG. 60 is a perspective view of an embodiment of a horizontal rodsystem, a vertical rod system and a connector of the invention.

FIG. 61 is a perspective view of an embodiment of a connector of theinvention.

FIG. 62A is a perspective view of an embodiment of a sliding tab of aconnector of the invention.

FIG. 62B is a perspective view of an embodiment of a sliding tab of aconnector of the invention.

FIG. 63 is a perspective view of an embodiment of a horizontal rodsystem, a vertical rod system and a connector of the invention.

FIG. 64 is a perspective view of an embodiment of a vertical rod of theinvention.

FIG. 65 is a perspective view of an embodiment of a horizontal rodsystem, a vertical rod system and a connector of the invention.

FIG. 66 is a perspective view of an embodiment of a connector of theinvention.

FIG. 67 is a perspective view of an embodiment of a vertical rod of theinvention.

FIG. 68 is a perspective view of an embodiment of a deflection rod ofthe invention.

FIG. 69 is a perspective and exploded view of an embodiment of adeflection rod of the invention.

FIG. 70 is a front view of an embodiment of a deflection rod of theinvention.

FIG. 71 is a front view of an embodiment of a deflection rod of theinvention.

FIG. 72A is a perspective view of an embodiment of a horizontal rodsystem, a vertical rod system and a connector of the invention.

FIG. 72B is a perspective view of an embodiment of a horizontal rodsystem, a vertical rod system and a connector of the invention.

FIG. 72C is a partial sectional view of an embodiment of a horizontalrod system, a vertical rod system and a connector of the invention.

FIG. 73A is a perspective view of an embodiment of a horizontal rodsystem and a connector of the invention.

FIG. 73B is a front view of a an embodiment of horizontal rod system ofthe invention.

FIG. 73C is a sectional view of an embodiment of a horizontal rod systemof the invention.

FIG. 74 is a perspective view of an embodiment of a horizontal rod ofthe invention.

FIG. 75 is a perspective view of an embodiment of a horizontal rod ofthe invention.

FIG. 76 is a perspective view of an embodiment of a horizontal rod ofthe invention.

FIG. 77A is a perspective view of an embodiment of a cam of theinvention.

FIG. 77B is a top view of an embodiment of a cam of the invention.

FIG. 78 is a perspective view of an embodiment of a cam of theinvention.

FIG. 79A is a perspective view of an embodiment of a horizontal rodsystem and a connector of the invention.

FIG. 79B is a perspective view of an embodiment of a horizontal rodsystem, a vertical rod system and a connector of the invention.

FIG. 80 is a perspective view of an embodiment of a connector of theinvention.

FIG. 81 is a perspective view of an embodiment of a connector of theinvention.

FIG. 82 is a perspective view of an embodiment of a horizontal rodsystem, a vertical rod system and a connector of the invention.

FIG. 83 is a perspective view of an embodiment of a rotating link of aconnector of the invention.

FIG. 84 is a sectional view of an embodiment of a horizontal rod system,a vertical rod system and a connector of the invention.

FIG. 85 is a sectional view of an embodiment of a horizontal rod system,a vertical rod system and a connector of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention include a system or implant andmethod that can dynamically stabilize the spine while providing forpreservation of spinal motion. Alternative embodiments can be used forspine fusion.

Embodiments of the invention include a construct with an anchoringsystem, a horizontal rod system that is associated with the anchoringsystem and a vertical rod system that is associated with the anchoringsystem and the horizontal rod system.

An advantage and aspect of the system is that the anchoring systemincludes a head or saddle that allows for appropriate, efficient andconvenient placement of the anchoring system relative to the spine inorder to reduce the force that is placed on the anchoring system. Theanchor system has enhanced degrees of freedom which contribute to theease of implantation of the anchor system. Accordingly, the anchorsystem is designed to isolate the head and the screw from the rest ofthe dynamic stabilization system and the forces that the rest of thedynamic stabilization system can place on the anchor system and theanchor system/bone interface. Thus, the anchor system can provide asecure purchase in the spine.

Another advantage and aspect of the system is that the horizontal rodsystem is in part comprised of a super elastic material that allows forconvenient positioning of the horizontal rod system relative to theanchor system and allows for isolation of the horizontal rod system fromthe anchor system so that less force is placed on the anchor system fromthe horizontal rod system and on the anchor system/bone interface.Accordingly, unlike prior devices the anchor system stays secure in thebone of the spine.

An aspect and advantage of the invention is the ability to maximize therange of motion of the spine after embodiments of the dynamicstabilization, motion preservation implant of the invention areimplanted in a patient. While traditional solutions to back pain includefusion, discectomy, and artificial implants that replace spinestructure, embodiments of the present invention preserve the bone andligament structure of the spine and preserve a wide range of motion ofthe spine, while stabilizing spines that were heretofore unstable due todegenerative and other spinal diseases.

Still another aspect of the invention is the preservation of the naturalmotion of the spine and the maintenance of the quality of motion as wellas the wide range of motion so that the spine motion is as close to thatof the natural spine as possible. The present embodiments of theinvention allow for the selection of a less stiff, yet dynamicallystable implant for use in a non-fusion situation. A less stiff, yetdynamically stable implant relates directly to a positive patientoutcome, including patient comfort and the quality of motion of thespine.

In another aspect of the invention, load sharing is provided by theembodiment, and, in particular, the deflection rod or loading rod of theembodiment. For embodiments of this invention, the terms “deflectionrod” and “loading rod” can be used interchangeably. Accordingly thisaspect of the invention is directed to restoring the normal motion ofthe spine. The embodiment provides stiffness and support where needed tosupport the loads exerted on the spine during normal spine motion, whichloads, the soft tissues of the spine are no longer able to accommodatesince these spine tissues are either degenerated or damaged. Loadsharing is enhanced by the ability to select the appropriate stiffnessof the deflection rod or loading rod in order to match the load sharingdesired. By selecting the appropriate stiffness of the deflection rod orloading rod to match the physiology of the patient and the loads thatthe patient places on the spine, a better outcome is realized for thepatient. Prior to implantation of the embodiment, the stiffness of theimplant of the system can be selected among a number of loading rods. Inother words, the stiffness is variable depending on the deflection rodor loading rod selected. In another aspect, the load sharing is betweenthe spine and the embodiment of the invention.

In another aspect of the invention, the deflection rod or loading rod iscantilevered. In another aspect the deflection rod or loading rod iscantilevered from a horizontal rod. In yet another aspect the deflectionrod or loading rod is cantilevered from a horizontal rod that isconnected between two anchors that are affixed to the same vertebra. Inyet another aspect the deflection rod or loading rod is about parallelto the horizontal rod in a resting position. In still a further, aspectthe deflection rod or loading rod is cantilevered from a mount on thehorizontal rod and said deflection rod or loading rod is about parallelto the horizontal rod in a resting position.

In another aspect of the invention the horizontal rod attached directlyto opposite anchors is stiff and rigid, and the cantilevered deflectionrod or cantilevered loading rod shares the load with the spine resultingfrom the motions of the body of the patient.

In another aspect of embodiments of the invention, the load beingabsorbed or carried by the embodiment is being distributed along atleast part of the length of the deflection rod or loading rod. Inanother aspect of the invention, the load being absorbed or carried bythe embodiment is distributed along at least part of the length of thehorizontal cantilevered deflection rod or horizontal cantileveredloading rod.

As the load is carried horizontally along the deflection rod or loadingrod, rather than vertically, the embodiments of the invention can bemade smaller in order to fit in more spaces relative to the spine.Advantageously, the embodiments can fit in the L5-S1 space of the spine.

An aspect of the invention is to preserve and not restrict motionbetween the pedicles of the spine through the use of appropriatelyselected horizontal and vertical rods of embodiments of the invention.

An aspect of the invention is to provide for load bearing on horizontalelements such as horizontal rods instead of vertical elements or rods,and, in particular, vertical elements that are connected between boneanchoring systems.

An aspect of the invention is the use of horizontal rods in theembodiments of the invention in order to isolate each level of theimplantation system from the other so as not to put undue force and/ortorque on anchoring systems of embodiment of the invention andassociated bone, and so as to allow customization of the implantationsystem to the need of the patient. Accordingly, an aspect of theinvention is to provide for minimized loading on the bone/implantationsystem interface. Customization, in preferred embodiments, can beachieved by the selection of the horizontal rod with the desiredstiffness and stiffness characteristics. Different materials anddifferent implant configurations enable the selection of variousstiffness characteristics.

Another aspect of the invention is the ability to control stiffness forextension, flexion, lateral bending and axial rotation, and to controlstiffness for each of these motions independently of the other motions.

An aspect of the invention is to use the stiffness and load bearingcharacteristics of super elastic materials.

Another aspect of the invention is to use super elastic materials tocustomize the implant to the motion preservation and the dynamicstabilization needs of a patient. An aspect of such embodiments of theinvention is to provide for a force plateau where motion of theimplantation system continues without placement of additional force ofthe bone anchor system, or, in other words, the bone/implantation systeminterface.

Thus, an aspect of the invention is to use the horizontal bar to offsetloading on the anchor system and on the implantation system in general.

Accordingly, an aspect of the invention is to be able to selectivelyvary the stiffness and selectively vary the orientation and directionthat the stiffness is felt by varying the structure of the implantationsystem of the invention, and, in particular, to vary the stiffness ofthe horizontal rod system of the invention.

Another aspect of embodiments of the invention is to prevent anyoff-axis implantation by allowing the implantation system to haveenhanced degrees of freedom of placement of the implant. Embodiments ofthe invention provide for off-axis placement of bone anchor or pediclescrew systems.

A further aspect of embodiments of the invention is to controlstabilized motion from micro-motion to broad extension, flexion, axialrotation, and lateral bending motions of the spine.

Yet another aspect of the embodiments of the invention is to be able torevise a dynamic stabilization implant should a fusion implant beindicated. This procedure can be accomplished by, for example, theremoval of the horizontal rods of the implantation system andreplacement of such rods with stiffer rods. Accordingly, an aspect ofthe invention is to provide for a convenient path for a revision of theoriginal implantation system, if needed.

A further aspect of the invention, due to the ease of implanting theanchoring system and the ease of affixing vertical rods to thehorizontal rods of the invention, is the ability to accommodate the bonestructure of the spine, even if adjacent vertebra are misaligned withrespect to each other.

A further aspect of the invention is that the implant is constructedaround features of the spine such as the spinous processes and, thus,such features do not need to be removed and the implant does not get inthe way of the normal motion of the spine features and the spinefeatures do not get in the way of the operation of the implant.

Another aspect of embodiments of the invention is the ability tostabilize two, three and/or more levels of the spine by the selection ofappropriate embodiments and components of embodiments of the inventionfor implantation in a patient. Further embodiments of the inventionallow for fused levels (in conjunction with, if desired, bone graphs) tobe placed next to dynamically stabilized levels with the sameimplantation system. Such embodiments of the invention enable vertebrallevels adjacent to fusion levels to be shielded by avoiding an abruptchange from a rigid fusion level to a dynamically stable, motionpreserved, and more mobile level.

Accordingly, another aspect of the embodiments of the invention is toprovide a modular system that can be customized to the needs of thepatient. Horizontal rods can be selectively chosen for the particularpatient as well the particular levels of the vertebrae of the spine thatare treated. Further, the positioning of the various selected horizontalrods can be selected to control stiffness and stability.

Another aspect of embodiments of the invention is that embodiments canbe constructed to provide for higher stiffness and fusion at one levelwhile allowing for lower stiffness and dynamic stabilization at anotheradjacent level.

Yet a further aspect of the invention is to provide for dynamicstabilization and motion preservation while preserving the bone andtissues of the spine in order to lessen trauma to the patient and to usethe existing functional bone and tissue of the patient as optimally aspossible in cooperation with embodiments of the invention.

Another object of the invention is to implant the embodiments of theinvention in order to unload force from the spinal facets and otherposterior spinal structures and also the intervertebral disk.

A further aspect of the invention is to implant the embodiment of theinvention with a procedure that does not remove or alter bone or tear orsever tissue. In an aspect of the invention the muscle and other tissuecan be urged out of the way during the inventive implantation procedure.

Accordingly, an aspect of the invention is to provide for a novelimplantation procedure that is minimally invasive.

Dynamic Stabilization, Motion Preservation System for the Spine:

A dynamic stabilization, motion preservation system 100 embodiment ofthe invention is depicted in FIG. 1 and includes an anchor system 102, ahorizontal rod system 104, and a vertical rod system 106. For theseembodiments horizontal refers to a horizontal orientation with respectto a human patient that is standing and vertical refers to a verticalorientation with respect to a patient that is standing (FIG. 1A). Aswill be more fully disclosed herein below, one embodiment for the anchorsystem 102 includes a bone screw 108 which is mounted to a head orsaddle 110. Alternatively, the bone screw 108 can be replaced by a bonehook as more fully described in U.S. Provisional Patent Application No.60/801,871, entitled “An Implant Position Between the Lamina to TreatDegenerative Disorders of the Spine,” which was filed on Jun. 14, 2006,and is incorporated herein by reference and in its entirety. Themounting of the head or saddle 110 to the bone screw 108 allows formultiple degrees of freedom in order that the bone screw 108 may beappropriately, conveniently, and easily placed in the bone of the spineand in order to assist in isolating the bone screw 108 from theremainder of the system 100 so that less force is placed on the anchorsystem 102 and on the bone screw/bone interface. Some prior art devices,which use such bone screws, have, on occasion, had the bone screwsloosen from the spine, and the present embodiment is designed to reducethe force on the bone screw and on the bone screw/bone interface.Preferably, the anchor system 102 is comprised of titanium. However,other biocompatible materials such as stainless steal and/or PEEK can beused.

In the embodiment of Fig. 1, the horizontal bar system 104 is preferablysecured through the head 110 of the anchor system 102 with a locking setscrew 112. This embodiment includes a first horizontal rod 114 and asecond horizontal rod 116. The first horizontal rod 114 has first andsecond deflection rods or loading rods 118 and 120 secured thereto. In apreferred embodiment, the first horizontal rod can be comprised oftitanium, stainless steel or PEEK or another biocompatible material, andthe first and second deflection rods or loading rods can be comprised ofa super elastic material. Preferably, the super elastic material iscomprised on Nitinol (NiTi). In addition to Nitinol or nickel-titanium(NiTi), other super elastic materials include copper-zinc-aluminum andcopper-aluminum-nickel. However, for biocompatibility, thenickel-titanium is the preferred material.

Such an arrangement allows for the horizontal rod system 104 to isolateforces placed thereon from the anchor system 102 and, thus, isolateforces that could be placed on the bone screw 108 and the bonescrew/bone interface of the spine, and, thus, prevent the loosening ofthe bone screw 108 in the spine. As shown in FIG. 1 the deflection rodsor loading rods 118 and 120, in this preferred embodiment, are mountedin the center of the first horizontal rod 114 to a mount 122.Preferably, the deflection rods or loading rods 118 and 120 are forcefit into the mount 122. Alternatively, the deflection rods or loadingrods may be screwed, glued, or laser welded to the mount 122 and tobores placed in the mount 122. Other fastening techniques are within thescope and spirit of the invention. As can be seen in FIGS. 1, 3, and 4,the first horizontal rod 114 includes first and second ridges 124, 126located on either side of the mount 122 and extend at least partiallyalong the length of the first horizontal rod 114 toward the respectiveends of the horizontal rod 114. These ridges 124, 126 add rigidity tothe mount 122 relative to the rest of the horizontal rod system 104.

As seen in FIG. 1, the deflection rods or loading rods 118, 120 have aconstant diameter extending outwardly toward the respective ends 128,130 of the deflection rods or loading rods 118, 120. Alternatively, thedeflection rods or loading rods 118, 120 can have a varying diameter asthe rods 118, 120 approach their respective ends 128, 130. Preferably,as depicted and discussed below, the rods 118 and 120 can have adecreasing diameter as the rods approach the respective ends 128, 130.The decreasing diameter allows the super elastic rods 118, 120 to bemore flexible and bendable along the length of the rods as the rodsapproach the ends 128, 130 and to more evenly distribute the load placedon the system 100 by the spine. Preferably, the diameter of thedeflection rods or loading rods continuously decreases in diameter.However, it can be understood that the diameter can decrease in discretesteps along the length, with the diameter of one step not beingcontinuous with the diameter of the next adjacent step. Alternatively,for different force and load carrying criteria the diameters of thedeflection rods or loading rods can continuously increase in diameter orcan have discreet step increases in diameter along the length of thedeflection rods or loading rods as the rods extent toward the respectiveends 128, 130. Still further, the rods can have at least one step ofdecreasing diameter and at least one step of increasing diameter in anyorder along the length of the deflection rods or loading rods as therods approach the respective ends 128, 130, as desired for the force andload carrying characteristics of the deflection rods or loading rods118, 120.

With respect to FIG. 3, for example, the horizontal rod system 104, and,in particular, the deflection rods 118, 120, share the load carried bythe spine. This load sharing is directed to restoring the normal motionof the spine. This embodiment, and, in particular, the deflection rodsor loading rods 118, 120, provide stiffness and support where needed tosupport the loads exerted on the spine during spine motion, which loads,the soft tissues of the spine are no longer able to accommodate sincethese spine tissues are either degenerated or damaged. Such load sharingis enhanced by the ability to select the appropriate stiffness of thedeflection rods or loading rods 118, 120 in order to match the loadsharing desired. By selecting the appropriate stiffness of thedeflection or loading rods, to match the physiology of the patient, andthe loads that the patient places on the spine, a better outcome isrealized by the patient. Prior to implantation, the stiffness of thedeflection or loading rods can be selected from a number of deflectionor loading rods. The stiffness is variable depending on the deflectionor load rod selected. As indicated herein, the stiffness of thedeflection or loading rod can be varied by the shape of the rod and theselection of the material. Shape variations can include diameter, taper,direction of taper, stepped tapering, and material variation can includecomposition of material, just to name a few variations.

It is to be understood that the load carried by the deflection orloading rods is distributed along at least part of the length of thedeflection or loading rods. Preferably, the load is distributed alongthe entire length of the deflection or loading rods. Further, as theload is carried horizontally and the stiffness can be varied along ahorizontal member, rather than vertically, the embodiments of theinvention can be made smaller in order to fit in more spaces relative tothe spine. Advantageously, embodiments can fit, for example, in theL5-S1 space of the spine in addition to generally less constrainedspaces such as the L4-L5 space of the spine.

With respect to the embodiment of the horizontal rod system of theinvention as depicted for example in FIG. 3, the deflection rods orloading rods 118, 120 are cantilevered from mount 122. Thus, thesedeflection rods 118, 120 have a free end and an end fixed by the mount112, which mount is located on the horizontal rod 114. As is evident inFIG. 3, the cantilevered deflection rods 118, 120 are about parallel ina rested position to the horizontal rod 114, and, in this embodiment,the horizontal rod is directly connected to the anchor systems and, inparticular, to the heads or saddles of the anchor system. Preferably,the horizontal rod 114 is stiff and rigid and, particularly, incomparison to the deflection rods. In this arrangement, the horizontalrod system and, in particular, the deflection rods 118, 120 share theload resulting from the motions of the body of the patient.

As an alternate embodiment, the second horizontal rod 116 could bereplaced with a horizontal rod 114 which has deflection rods or loadingrods (FIG. 43A). Thus, both horizontal rods would have deflection rodsor loading rods. The deflection rods or loading rods mounted on onehorizontal rod would be connected to vertical rods and the vertical rodswould be connected to deflection rods or loading rods mounted on theother horizontal rod. Such an embodiment provides for more flexibility.Further, the deflection rods or loading rods 118, 120 can have otherconfigurations and be within the spirit and scope of the invention.

Further, as can be seen in FIG. 1, the vertical rod system is comprisedof, in this embodiment, first and second vertical rods 132, 134 whichare secured to first and second connectors 136, 138 located at the ends128, 130 of the first and second deflection rods or loading rods 118,120. As will be described below, the vertical rods 132, 134 arepreferably connected in such a way as to be pivotal for purposes ofimplantation in a patient and for purposes of adding flexibility anddynamic stability to the system as a whole. These vertical rods 132, 134are preferably made of titanium. However, other bio-compatible materialscan be used. The vertical rods 132, 134 are also connected to the secondhorizontal rod 116 by being received in C-shaped mounts 140, 142 locatedon the second horizontal rods and in this embodiment, held in place byset screws 144,146. It is to be understood by one of ordinary skill inthe art that other structures can be used to connect the vertical rodsto the horizontal rods.

Preferably, the vertical rods are only connected to the horizontal rodsand not to the anchoring system 102 in order to isolate the anchorsystem 102 and, in particular, the heads 110 from stress and forces thatcould be placed on the heads, and from forces transferred to the headswhere the vertical rods connect to the heads. Thus, the system 100through the vertical and horizontal rods allow for dynamic stability,and a wide range of motion without causing undue force to be placed onthe heads of the anchor systems. These embodiments also allow for eachlevel of the spine to move as freely as possible without being undulyrestrictively tied to another level.

More lateral placement of the vertical rods toward the heads of theanchor system provides for more stiffness in lateral bending and aneasier implant approach by, for example, a Wiltse approach as describedin “The Paraspinal Sacraspinalis-Splitting Approach to the LumberSpine,” by Leon L. Wiltse et al., The Journal of Bone & Joint Surgery,Vol. 50-A, No. 5, July 1968, which is incorporated herein by reference.

The stiffness of the system 100 can preferably be adjusted by theselection of the materials and placement and diameters of the horizontaland vertical rods and also the deflection rods or loading rods. Largerdiameter rods would increase the resistance of the system 100 toflexion, extension rotation, and bending of the spine, while smallerdiameter rods would decrease the resistance of the system 100 toflexion, extension, rotation and bending of the spine. Further,continually or discretely changing the diameter of the rods such as thedeflection rods or loading rods along the length of the rods changes thestiffness characteristics. Thus, with the deflection rods or loadingrods 118, 120 tapered from the mount 122 toward the ends 128, 130, thesystem can have more flexibility in flexion and extension of the spine.Further, using a super elastic material for the horizontal rods and thevertical rods in addition to the horizontal deflection rods or loadingrods adds to the flexibility of the system 100. Further, all of thehorizontal and vertical rods, in addition to the deflection rods orloading rods, can be made of titanium or stainless steel or PEEK shoulda stiffer system 100 be required. Thus, it can be appreciated that thesystem 100 can easily accommodate the desired stiffness for the patientdepending on the materials uses, and the diameter of the materials, andthe placement of the elements of the system 100.

Should an implanted system 100 need to be revised, that can beaccomplished by removing and replacing the horizontal and/or verticalrods to obtain the desired stiffness. By way of example only, should astiffer revised system be desired, more akin to a fusion, or, in fact, afusion, then the horizontal rods having the deflection rods or loadingrods can be removed and replaced by horizontal rods having deflectionrods or loading rods made of titanium, or stainless steel, or non-superelastic rods to increase the stiffness of the system. This can beaccomplished by leaving the anchor system 102 in place and removing theexisting horizontal rods from the heads 110 and replacing the horizontalrods with stiffer horizontal rods and associated vertical rods.

FIG. 3 depicts a view of the horizontal rod 104 as previously described.In this embodiment the connectors 136, 138 are shown on the ends of thedeflection rods or loading rods 118, 120. The connectors can beforced-fitted to the deflection rods or fastened in other methods knownin the art for this material and as further disclosed below. Theconnectors 136, 138 have slits 148, 150 to aid in placing the connectorsonto the ends of the deflection rods. As is evident from FIG. 3, theconnectors 136, 138 each include upper and lower arms 160, 162 which cancapture there between the vertical rods 132, 134. The arms each includean aperture 168, 170 that can accept a pin or screw 176, 178 (FIG. 1)for either fixedly or pivotally securing the vertical rods 132, 134. Inthis embodiment the vertical rods include a head 162, 164 that can beforce fit or screwed onto the rest of the vertical rods. The headsinclude apertures 172, 174 for accepting the pins or screws 176, 178.

In order that the system 100 has as low a profile as possible andextends from the spine as little as possible, it is advantageous toplace the deflection rods or loading rods 118, 120 as close to the firsthorizontal rod 114 as possible. In order to accomplish this low profile,preferably notches 152, 154 are placed in horizontal rod 114 toaccommodate the connectors 136, 138.

Accordingly, the purpose for the notches is to provide for a horizontalrod with a low profile when implanted relative to the bones and tissuesof the spine so that there is, for example, clearance for implant andthe motion of the implant, and to keep the deflection rods or loadingrods as close as possible to the horizontal rods in order to reduce anypotential moment arm relative to the mounts on the horizontal rod.

FIG. 4 depicts another embodiment of the horizontal rod 114 withdeflection rods or loading rods 118, 120 and with different connectors156, 158. Connectors 156, 158 each include two pairs of upper and lowerarms 160, 162 extending in opposite directions in order for eachconnector 156, 158 to mount an upper and a lower vertical rod aspresented with respect to FIG. 46. This configuration allows for a threelevel system as will be described below.

Embodiments of the Anchor System of the Invention

A preferred embodiment of the anchor system 102 invention can be seen inFIG. 5. This is similar to the anchor system 102 depicted in FIG. 1. Inparticular, this anchor system 102 includes a bone screw 108 with a head110 in the form of a U-shaped yoke 180 with arms 182, 184. As will bediscussed further, a hook, preferably with bone engaging barbs orprojections, can be substituted for the bone screw 108. The hookembodiment is further described in the above referenced and incorporatedprovisional application. The hooks are used to hook to the bone, such asthe vertebra instead of having screws anchored into the bone. Each ofthe arms 182, 814 of yoke 180 includes an aperture 186, 188 throughwhich a pin 190 can be placed. The pin 190 can be laser welded or forcefit or glued into the yoke 180, as desired. The pin 190 can be smooth orroughened as discussed below. Further, the pin 190 can be cylindrical orbe comprised of a multiple sides as shown in FIG. 7. In FIG. 7, pin 190has six sides and one or more of the accommodating apertures 186, 188can also include mating sides in order to fix the position of the pin190 in the yoke 180. A compression sphere 200 is placed over the pin190. The compression sphere 200 can have a roughened surface if desiredto assist in locking the sphere in place as described below. Thecompression sphere 200 can include one or more slits 202 to assist incompressing the sphere 200 about the pin 190. The compression sphere 200can have an inner bore that is cylindrical or with multiple sides inorder conform to and be received over the pin 190. As can be seen inFIG. 8, one or more spacer rings 204 can be used to space thecompression ring from the yoke 180 in order to assist in providing therange of motion and degrees of freedom that are advantageous to theembodiments of the invention.

Mounted about the compression sphere 200 is the head or saddle 110. Head110 in FIGS. 7, 8 is somewhat different from head 110 in FIG. 1 as willbe described below. Head 110 in FIGS. 7, 8 includes a cylindrical body206 with a lower end having an aperture 208 that can receive thecompression sphere 200. The aperture 208 can have a concave surface asdepicted in Figs.7, 8. Accordingly, the compression sphere 200 fitsinside of the concave surface of aperture 208 and is free to movetherein until restrained as described below. As is evident from thefigures, the lower end of the cylindrical body 206 about the aperture208 has some of the material that comprised wall 224 removed in order toaccommodate the motion of the yoke 180 of the bone screw 108.Essentially, the portion of the wall 224 adjacent to the arms 182, 184of the yoke 180 has been removed to accommodate the yoke 180 and therange of motion of the yoke.

The head 110 of the anchor system 102 includes an internal cylindricalbore 210 which is preferably substantially parallel to a longitudinalaxis of the head 110. This bore 210 is open to the aperture 208 and isopen and preferably substantially perpendicular to the distal end 212 ofthe head 110. At the distal end 212 of the head 110, the bore 210 isthreaded and can accept the set screw 112. Along the side of the head110 are defined aligned U-shaped slots that extend through the head 110from the outer surface to the bore 210. These U-shaped slots are alsoopen to the distal end 212 of the head 110 in order to have the setscrew 112 accepted by the threads of the bore 210. Located in the bore210 between the set screw 112 and the compression sphere 200 is acompressor element or cradle 220. The compressor element or cradle 220can slide somewhat in the bore 210, but the compressor element or cradle220 is restrained by a pin 222 (FIG. 7) received through the wall 224 ofthe head 110 and into the compressor element or cradle 220. Thus, thecompressor element or cradle 220, until locked into position, can movesomewhat in the bore 210.

The compressor element or cradle 220 has a generally cylindrical body sothat the compressor element 220 can fit into bore 210. An upper end 226of the compressor element 220 includes a concave surface 228. Thissurface 228 is shaped to fit the horizontal rod system 104 and, inparticular, a horizontal rod 114, 116. The lower end of the compressorelement 220 includes a concave surface 230 which can accommodate thecompression sphere 200. The lower end of the compressor element 220adjacent to the concave surface 230 has an additional concave surface232 (FIG. 8) which is used to accommodate the motion of the upper end ofthe yoke 180 as the head 110 is moved relative to the bone screw 108.The concave surfaces 228 and 230 can be roughened, if desired, to assistin locking the head 110 relative to the bone screw 108. In thisembodiment (FIGS. 5, 6) there is no top compression element or cradle(see, for example, FIGS. 7, 13) in order to reduce the profile of thehead of the anchor system.

As is evident from the figures, with the anchor system 102 assembled andwith a horizontal rod 114, 116 received in the U-shaped slot 216, theset screw can press against the horizontal rod 114, 116, whichhorizontal rod 114, 116, can press against the compressor element orcradle 220, which compressor element or cradle 220 can press against thecompression sphere 220, which compression sphere can press against thepin 190 in order to lock the horizontal rod 114, 116 relative to thehead 110 and to lock the head 110 relative to the bone screw 108. It isto be understood that all of the surfaces that are in contact, can beroughened to enable this locking, if desired. Alternatively, thesurfaces may be smooth with the force of the set screw 112 urging of theelements together and the resultant locking.

As can be seen in FIGS. 5, 6 an alternative horizontal rod 114, 116 isdepicted. This alternative horizontal rod 114, 116 includes first andsecond concave openings 234, 236 which can receive vertical rods such asvertical rods 132, 134 (FIG. 1). The horizontal rod 114, 116 issubstantially cylindrical with the areas around the concave openings234, 236 bulked up or reinforced as desired to support the forces.Additionally, threaded bores are provided adjacent to the concaveopenings 234, 236 and these bores can receive screws that have headsthat can be used to lock vertical rods in place. Alternatively, thescrews can retain short bars that project over the concave openings 234,236 in order to hold the vertical rods in place (FIG. 34). If desired,the short retaining bars can also have concave openings that conform tothe shape of, and receive at least part of, the vertical rods in orderto retain the vertical rods in place with the system 100 implanted in apatient.

Turning again to FIGS. 1, 2, 5, 6, the head 110 depicted is a preferredembodiment and is somewhat different from the head 110 as seen in FIG.8. In particular the head body 206, the outer surface 218 of the headand the head wall 224, have been configured in order to prevent splayingof the head 110 when the set screw 112 locks the anchor system 102 asexplained above. As seen in FIGS. 1, 2, the head 110 and, in particular,the wall 224 is reinforced about the U-shaped slot 216 that received thehorizontal bar system 104. By reinforcing or bulking up the area of thewall about the U-shaped slot 216, splaying of the head 110 when force isapplied to the set screw 214, in order to lock the anchor system 102, isavoided. The head 110 can use a number of shapes to be reinforced inorder to prevent splaying. The exemplary embodiment of FIGS. 1, 2,includes a pitched roof shape as seen in the top view looking down ondistal end 212 of the head 110. In particular, the wall about theU-shaped slot 216 is thickened, while the portion of the head distalfrom the U-shaped slot can be less thick if desired in order to reducethe bulk and size of the head 110 and, thus, give the head 110 a smallerprofile relative to the bone and tissue structures when implanted in apatient. Further, the small profile allows greater freedom of motion ofthe system 100 as described below. Also, it is to be understood that dueto the design of the anchor system 102, as described above, the head 110can be shorter and, thus, stand less prominently out of the bone whenthe bone screw 108 in implanted in a spine of a patient for example.

Freedom of Motion of the Embodiments of the Anchor System of theInvention

In order to accommodate embodiments of the horizontal rod systems 104 ofthe invention, to allow greater freedom in placing the horizontal rodsystems and the anchor systems 102 relative to, for example, the spineof a patient, and to provide for a smaller implanted profile in apatient, the anchor system 102 includes a number of degrees of freedomof motion. These degrees of freedom of motion are depicted in FIGS. 9,9A, 10, 10A, and 11, 11A.

FIG. 9 establishes a frame of reference including a longitudinal axis xwhich is along the longitudinal length of the bone screw 108, a y axisthat extends perpendicular to the x axis, and a lateral axis z which isperpendicular to both the x axis and the y axis and extends outwardlyfrom and parallel to the pin 190 of the yoke 180 of the anchor system102. As depicted in the figures and, in particular, FIGS. 9, 9A, thesystem 100 due to the embodiments as disclosed herein is able to havethe head 110 rotate about the z axis from about 80 degrees to about zerodegrees and, thus, in line with the x axis and from the zero degreeposition to about 80 degrees on the other side of the x axis.Accordingly, the head is able to rotate about 160 degrees about the zaxis relative to the bone screw 108. As seen in FIGS. 10, 10A the head110 is able to tilt about 0.08 inches (2 mm) relative to and on bothsides of the x axis. Accordingly, the head 110 can tilt from about 12degrees to zero degrees where the head 110 is about parallel to the xaxis and from zero degrees to 12 degrees about the y axis and on theother side of the x axis. Thus, the head can tilt through about 24degrees about the y axis. As can be seen in FIGS. 11, 11A, the head 110can swivel for a total of about 40 degrees about the x axis. Withrespect FIG. 11A, the head 110 can swivel about the x axis from about 20degrees to one side of the z axis to zero degrees and from zero degreesto about 20 degrees on the other side of the z axis. The head is able tosubstantially exercise all of these degrees of freedom at once and,thus, can have a compound position relative to the bone screw bysimultaneously moving the head within the ranges of about 160 degreesabout the z axis (FIG. 9), about 24 degrees from the y axis (FIG. 10)and about 40 degrees about the x axis (FIG. 11A).

Thus, with respect to FIGS. 9, 9A the range of motion in the axial planeis about 180 degrees or about 90 degrees on each side of the centerline.In FIGS. 10, 10A the range of motion in the Caudal/Cephalad orientationis about 4 mm or about 2 mm on each side of the centerline or about 24degrees or about 12 degrees on each side of the centerline. In FIGS. 11,11A the range of motion in the coronal plane is about 40 degrees orabout 20 degrees on each side of the centerline.

FIGS. 12, 13 depict yet another embodiment of the anchor system 102 ofthe invention where elements that are similar to elements of otherembodiments and have similar reference numbers.

As can be seen in FIG. 13, this embodiment includes a lower cradle orcompressor element 220 that is similar to the cradle or compressorelement 220 of the embodiment of FIG. 7 with the head 110 similar to thehead 110 as seen in FIG. 7. The compression sphere 200 is similar to thecompression sphere 200 in FIG. 7 with the compression sphere including aplurality of slits provided about the axis of rotation 238 of the sphere200. In this embodiment, the slits 202 have openings that alternatebetween facing the north pole of the axis of rotation of the sphere 200and facing the south pole of the axis of rotation of the sphere 200.Alternatively, the slits can be provided in the sphere and have noopening relative to the north or south pole of the axis of rotation ofthe sphere 200. Still further, the slits can open relative to only oneof the north or south poles.

In the embodiment of FIGS. 12, 13, there is also an upper cradle orcompressor element 240 which is positioned adjacent to the set screw 214(see also FIG. 7). The upper cradle or compressor element 240 has agenerally cylindrical body which can slide in the cylindrical bore ofthe head 110 with an upper end having fingers 242 extending therefrom.The fingers 242 can spring over a bore formed in the lower surface ofthe set screw 214 in order to retain the cradle 240 relative to the setscrew 214 and to allow the cradle 240 to rotate relative to the setscrew 214. The lower surface of the cradle 240 includes a concavesurface 244 which can mate with a horizontal rod 114, 116 in order tolock the rod relative the head 110 and the head 110 relative to the bonescrew 108. If desired, the concave surface 244 can be roughened toassist in locking the system 100.

Further, in FIGS. 12, 13, a retaining ring 246 is depicted. Theretaining ring can be force fit over the outer surface 218 of the head110, or pop over and snap under a ridge 248 at the distal end 212 of thehead 110, or can have internal threads that mate with external threadslocated on the outer surface of the 218 of the head 110. With the anchorsystem 102 in place in a patient and with the horizontal rod 114, 116received in the anchor system, before the set screw 214 is tightened inorder to lock the horizontal rod and the anchor system, the retainingring 246 can be attached to the head 110 in order to prevent splaying ofthe head 110 as the set screw 214 locks the system 110.

Further embodiments of the anchor system 102 which can side load thehorizontal rods 114, 116 are seen in FIGS. 14, 15, and 16, where similarelements from other embodiments of the anchor system are given similarnumeral references. With respect to the embodiment in FIG. 15, the headside wall 224 includes a lateral or side opening 250 which communicateswith the cylindrical bore 210 which is located in head 110. The lateralor side opening preferably extends more than 180 degrees about the outersurface of the head. The side opening 250 includes a lip 252 and theside opening extends down below the lip into communication with thecylindrical bore 210 and follows the outline of the concave surface 228of the cradle 220. Accordingly, a horizontal rod 114, 116, can bepositioned through the side opening 250 and urged downwardly intocontact with the concave surface 228 of the cradle 220. In thisembodiment the cradle 220 includes a downward projecting post 254. Also,this embodiment does not include a compression sphere, and instead thepin 190, which can have a larger diameter than a pin 190 in otherembodiments, comes in direct contact with the post 254 when the setscrew 112 locks the anchor system 100. If desired the pin 190 can have aroughened surface 256 to assist in the locking of the anchor system 100.As is evident from FIGS. 14, 15, 16, as this embodiment has a sideloading head 110, the distal end of the head is a fully cylindricalwithout communicating with any lateral U-shaped slots of the otherembodiments. Accordingly, this embodiment does not include any retainingring or reinforced areas that can be used to prevent splaying.

FIG. 17 depicts yet another embodiment of the anchor system 102 that hasa lateral or side loading head 110. In this embodiment, a compressioncylinder 258 is placed over the pin 190. Such a compression cylinder 258may offer less freedom of motion of the anchor system 100 with addedstability. The compression cylinder 258 can slide along the longitudinalaxis 260 of the pin 190, if desired. The head 110 can rotate about thepin 190 and the compression cylinder 258. The head 110 can also slide ortranslate along the longitudinal axis 260 of the pin as well as thelongitudinal axis of the compression cylinder 258. Compression cylinder258 has slits 262 that can be configured similarly as the slits 202 ofthe other embodiments of the anchor system 100 described and depictedherein.

FIG. 18 depicts still another embodiment of the anchor system 100 thathas a lateral or side loading head 110. This embodiment includes acompression sphere 200 provided over a pin 190 which is similar to theother compression spheres 200 depicted and described herein.Accordingly, this embodiment has the freedom of motion described withrespect to the other embodiments which use a compression sphere.

It is to be understood that although each embodiment of the anchorsystem does not necessarily depict all the elements of anotherembodiment of the anchor system, that one of ordinary skill in the artwould be able to use elements of one embodiment of the anchor system inanother embodiment of the anchor system.

Embodiments of the Horizontal Rod System of the Invention

Embodiments of the horizontal rod system 104 of the invention includethe embodiments describes above, in addition to the embodiments thatfollow. An aspect of the horizontal rod system 104 is to isolate theanchor system 102 and reduce the stress and forces on the anchor system.This aspect is accomplished by not transmitting such stresses and forcesplaced on the horizontal rod system by, for example, flexion, extension,rotation or bending of the spine to the anchor system. This aspect thusmaintains the integrity of the placement of the anchor system in, forexample, the spine and prevents loosening of the bone screw or bone hookof the anchor system. In addition, various horizontal rod systems can beused to control the rigidity, stiffness and/or springiness of thedynamic stabilization system 100 by the various elements that comprisethe horizontal rod system. Further the horizontal rod system can be usedto have one level of rigidity, stiffness and/or springiness in onedirection and another level in a different direction. For example, thehorizontal rod system can offer one level of stiffness in flexion of thespine and a different level of stiffness in extension of the spine.Additionally, the resistance to lateral bending can be controlled by thehorizontal rod system. Select horizontal rod systems allow for moreresistance to lateral bending with other select horizontal rod systemsallow for less lateral bending. As discussed below, placement of thevertical rods also effects lateral bending. The more laterally thevertical rods are placed, the more stiff the embodiment is to lateralbending.

As is evident from the figures, the horizontal rod system connects tothe heads of the anchor system without the vertical rod systemconnecting to the heads. Generally, two anchor systems are secured toeach vertebral level with a horizontal rod system connected between thetwo anchor systems. This further ensures that less stress and force isplaced on the anchor systems secured to each level and also enablesdynamic stability of the vertebra of the spine. Accordingly, movement ofthe vertebra relative to each other vertebra, as the spine extends,flexes, rotates and bends, is stabilized by the horizontal rods and theentire system 100 without placing excessive force or stress on theanchor system as there are no vertical rods that connect the anchorsystems of one vertebra level with the anchor system of anothervertebra.

With respect to FIG. 19 through FIG. 25 another embodiment of thehorizontal rod system 304 of the dynamic stabilization system 300 isdepicted as used with an anchor system 102 of the embodiment depicted inFIG. 1. Also shown in FIGS. 19, 19A, is the vertical rod system 306. Thehorizontal rod system 304 includes first and second horizontal rods 308,310. It is to be understood that FIG. 19A shows a second image of onlythe horizontal rod 308 in a first undeployed position and that FIG. 19shows a deployed position with the horizontal rod 308 connected withvertical rods 306 and, thus, the entire system 300.

The horizontal rod 308 includes first and second aligned end rods 312,314 which are connected together with an offset rod 316 located betweenthe first and second end rods 312, 314. In this embodiment, thehorizontal rod 308 looks much like a yoke with the offset rod joiningeach of the end rods 312, 314 with a curved section 318, 320. At thejunction of the first end rod 312 and the offset rod 316 is a first bore322 which is aligned with the first end rod 312, and at the junction ofthe second end rod 314 and the offset rod 316 is a second bore 324 whichis aligned with the second end rod 314 and, thus, aligned with the firstend rod 312. Positioned in and extending from the first bore 322 is afirst deflection rod or loading rod 326 and positioned in and extendingfrom the second bore 324 is a second deflection rod or loading rod 328.As with the other deflection rods or loading rods, preferably deflectionrods or loading rods 324, 328 are made of a super elastic material suchas, for example, Nitinol (NiTi) and the rest of system 300 is comprisedof titanium, stainless steel, a biocompatible polymer such as PEEK orother biocompatible material. In addition to Nitinol or nickel-titanium(NiTi), other super elastic materials include copper-zinc-aluminum andcopper-aluminum-nickel. However, for biocompatibility thenickel-titanium is the desired material. The super elastic material hasbeen selected for the deflection rods as the stress or force/deflectionchart for a super elastic material has a plateau where the force isrelatively constant as the deflection increases. Stated differently, asuper elastic rod has a load (y) axis/deflection (x) axis curve whichhas a plateau at a certain level where the load plateaus or flattens outwith increased deflection. In other words, the rod continues to deflectwith the load staying constant at the plateau. In one embodiment, theload plateau is about 250 Newtons to about 300 Newtons. It is to beunderstood that the plateau can be customized to the needs of thepatient by the selection of the type and composition of the superelastic material. For some patients, the plateau should be lower, and,for others, the plateau should be higher. Accordingly, and, for example,at the plateau, additional force is not put on the anchor system 102and, thus, additional force is not put on the area of implantation ofthe bone screw 108 and the surrounding bone of the spine where the bonescrew 108 is implanted. The deflection rods or loading rods 326, 328 areforce fit, screwed, welded, or glued into the bores 322, 324 as desired.

The first and second deflection rods or loading rods 326, 328 extendfrom the respective bores 322, 324 toward each other and are joined by aY-shaped connector 330. The Y-shaped connector 330 includes a base 332which has opposed and aligned bores 334, 336 that can receive thedeflection rods or loading rods 326, 328 in a manner that preferablyallows the Y-shaped connector to pivot about the longitudinal axisdefined by the aligned first and second deflection rods or loading rods326, 328. The Y-shaped connector 330 includes first and second arms thatpreferably end in threaded bores 342, 344 that can receive the threadedends of the vertical bar system 306 as described below. Just behind thethreaded bores 342, 344 are recesses 346, 348 (FIG. 24) which are shapedto accept the offset rod 316 with the horizontal rod 308 in theundeployed configuration depicted in FIG. 19A. In the undeployedconfiguration, the horizontal rod 308 can be more easily implantedbetween the tissues and bones of the spine and, in particular, guidedbetween the spinous processes. Once the first horizontal rod 308 isimplanted, the Y-shaped connector 330 can be deployed by rotating itabout 90 degrees or as required by the anatomy of the spine of thepatient and connected with the vertical rod system 306.

The second horizontal rod 310 is similar to the second horizontal rod116 of the embodiment of FIG. 1. This second horizontal rod 310 ispreferably comprised of titanium or other biocompatible material andincludes first and second mounts 350, 352 which can receive the ends ofthe vertical rod system 306. The mounts 350, 352 include respectiverecesses 354, 356 which can receive the vertical rods 358, 360 of thevertical rod system 306. The mounts 350, 352 also include tabs 362, 364which can capture the vertical rods 358, 360 in the respective recesses354, 356. The tabs 362, 364 can be secured to the mounts 350, 352 withscrews or other appropriate fastening devices.

The first and second vertical rods 358, 360 are preferably comprised oftitanium or other biocompatible material and include a threaded end anda non-threaded end. The threaded end can be formed on the end of the rodor threaded elements can be force fit or glued to the end of thevertical rods 358, 360. Once the first and second horizontal rods aredeployed in the patient, the first and second vertical rods can bescrewed into or otherwise captured by the Y-shaped connector 330 of thefirst horizontal bar 308 and the first and second vertical rods can becaptured or otherwise secured to the second horizontal bar 3 10.

FIGS. 26, 27, and FIGS. 28, 29 depict yet more alternative embodimentsof the horizontal rod systems of the invention. The horizontal rod 370in FIG. 26, 27 is similar to the horizontal rod 118 in FIG. 1.Horizontal rod 370 includes a mount 372 which has bores that can receivefirst and second deflection rods or loading rods 374, 376 which arepreferably made of a super elastic material. At the ends of the firstand second deflection rods or loading rods 374, 376 are connectors whichinclude a tab having a threaded bore therethrough. The connectors can beused to connect vertical rods to the deflection rods or loading rods.

FIGS. 28, 29 depict a horizontal rod 380 with first mount 382 and secondmount 384. Each of the mounts 382, 884, includes a bore that issubstantially parallel to the horizontal rod 380. First and seconddeflection rods or loading rods 386, 388 extend respectively from thebores of the first and second mounts 382, 382. In the embodimentdepicted the deflection rods or loading rods 386, 388 are parallel tothe horizontal rod 380 and are directed toward each other.Alternatively, the deflection rods or loading rods 386, 388 can bedirected away from each other. In that configuration, the mounts 382,384 would be spaced apart and the deflection rods or loading rods wouldbe shorter as the deflection rods or loading rods extended parallel toand toward the ends of the horizontal rod 380.

FIGS. 30, 31, 32 depict yet another embodiment of the horizontal rodsystem 390 of the invention which is similar to the horizontal barsystem 104 as depicted in FIG. 1. Horizontal bar system 390 includestapered deflection rods or loading rods 392, 394. The deflection rods orloading rods are tapered and reduce in diameter from the mount 396toward the ends of the horizontal rod 390. As previously discussed thedeflection rods or loading rods can taper continuously or in discretesteps and can also have an decreasing diameter from the ends of thedeflection rods or loading rods towards the mount 396. In other words, areverse taper than what is depicted in FIG. 30. Connected to thedeflection rod or loading rods 392, 394 are the vertical rods 402, 404.The vertical rods 402, 404 are connected to the deflection rods orloading rods 392, 394 as explained above.

The conically shaped or tapered deflection rods or loading rods can beformed by drawing or grinding the material which is preferably a superelastic material. The tapered shape of the deflection rods or loadingrods distributes the load or forces placed by the spine on the systemevenly over the relatively short length of the deflection rods orloading rods as the rods extend from the central mount outwardly towardthe ends of the horizontal rod. In this embodiment, in order to beoperatively positioned relative to the spine and between the anchorsystems, the deflection rods or loading rods are less than half thelength of the horizontal rods.

FIG. 30 depicts the vertical rods 402, 404 in undeployed positions thatare about parallel to the horizontal rod 390 and with the vertical rods402, 404 directed away from each other and toward the respective ends ofthe horizontal rod 390. In this position the horizontal rod 390 can bemore conveniently directed through the bone and tissue of the spine and,for example, directed between the spinous processes to the implantposition. Once in position, the vertical rods 402, 404 can be deployedso that the vertical rods are parallel to each other and about parallelto the horizontal rod 390 as depicted in FIG. 31. Accordingly, thisembodiment can be inserted from the side of the spine in the undeployedconfiguration depicted in FIG. 30 and then the vertical rods can berotated or deployed by about 90 degrees (from FIG. 30 to FIG. 31) eachinto the coronal plane of the patient. The vertical rods are also freeto rotate about 180 degrees about the deflection rods and in thesagittal plane of patient. This allows this embodiment to conform to thedifferent sagittal contours that may be encountered relative to thespine of a patient. The deflection rods or loading rods are rigidlyconnected to the horizontal rod allowing for an easier surgicaltechnique as sections of the spine and, in particular, the spinousprocesses and associated ligaments and tissues do not have to be removedin order to accommodate the implantation system 100. The moving actionof the system, and, in particular, the flexing of the deflection rodsand the motion of the vertical rods connected to the deflection rods orloading rods, takes place about the spinous processes and associatedtissues and ligaments, and, thus, the spinous processes do not interferewith this motion. Further, having the horizontal rods more lateral thancentral also allows for a more simple surgical technique through, forexample, a Wiltse approach.

To assist in implantation, a cone 406 can be slipped over the end of thehorizontal rod 390 and the vertical rod 402 to assist in urging thetissues and bone associated with the spine out of the way. Once thehorizontal rod is implanted the cone 406 can be removed. The cone 406includes an end 408 which can be pointed or bulbous and the cone 406 hasan increasing diameter in the direction to the sleeve 410 portion of thecone 406. The sleeve can be cylindrical and receive the end of thehorizontal rod and the end of the deflection rod or loading rod 402.

FIG. 32 depicts how the connectors 412, 414 are secured to therespective deflection rods 392, 394. The deflection rods have flanges,such as spaced apart flange 416, 418 on the deflection rod 392. Theconnectors 412, 414 can snap over and be retained between respectivepairs of flanges.

FIG. 33 depicts yet another embodiment of the horizontal rod system 430of the invention. The horizontal rod system 430 includes horizontal rod432 which is preferably comprised of a super elastic material such asNitinol. The horizontal rod 432 includes a generally central platform434, and on each side of the central platform 434 are first and secondupwardly facing scallops or recesses 436, 438. On each side of theupwardly facing scallop or recess 436 are downwardly facing scallops orrecesses 440, 442. On each side of the upwardly facing scallop or recess438 are downwardly facing scallops or recesses 444, 446. The platform434 accepts a connector for connecting the horizontal rod to verticalrods (FIG. 40) as will be explained below, and the scallops 436, 440,442 on one side of the platform 434 act as a spring and the scallop 438,444, 446 on the other side of the platform 434 acts as a spring. Thesesprings assist the platform in carrying the load that the spine canplace on the horizontal rod and isolate the anchor systems 102 from thatload. That isolation has the advantage of preventing loosening of theanchor system as implanted in the patient. It is to be understood thatby varying the pattern of the scallops, that the stiffness or rigidityof the horizontal bar can be varied and customized for each patient.Fewer scallops will generally result in a more stiff horizontal bar andmore scallops will generally result in a less rigid horizontal bar.Additionally, the stiffness can be different depending on the directionof the force that is placed on the horizontal bar depending on theorientation and location of the scallops. For the embodiment depicted inFIG. 33, with the scallops 436, 438 pointed upward to the head of apatient and the scallops 440, 442, 444, 446 pointed downward toward thefeet of a patient, the horizontal bar is stiffer in extension and lessstiff in flexion. It is noted that in this embodiment the rod is of auniform diameter, although the diameter can be non-uniform as, forexample, being larger where the platform 434 is and tapering to the endsof the horizontal rod 432, or having a large diameter at the ends of thehorizontal rod 432, tapering to a smaller diameter at the platform 434.In this embodiment with a substantially uniform diameter, the scallopsare formed within the uniform diameter. In other forms, the scallops aremolded into the horizontal rod or machined out of the preformedhorizontal rod. With this configuration, the horizontal rod is moreeasily inserted into the spine and between bones and tissues of thespine. Further, this horizontal rod can be more easily delivered to thespine through a cannula due to the substantially uniform diameter. Forpurposes of forming the scallops a machining technique known as wireelectric discharge machining or wire EDM can be used. Thus, an approachfor shaping the super elastic material is through wire EDM followed byelectro-polishing. Additionally, the super elastic material in this andthe other embodiments can be cold rolled, drawn or worked in order toincrease the super elastic property of the material.

In this embodiment, the deflection takes place almost exclusively in themiddle portion of the horizontal rod and principally at the platform andspring thus relieving the load or force on the ends of the horizontalrod and on the anchor system/bone interface.

Accordingly, in this preferred embodiment, there are two superiorscallops pointing upwardly having a relatively gentler radius comparedto the tighter radii of the inferior scallops pointing downwardly. It isto be understood that in this preferred embodiment, the inferiorscallops are not symmetrical the way the superior scallops are. Thelateral most cuts in both of the most lateral inferior scallops aresteep and not radiused. These cuts allow the rod to bend at these pointsenhancing the spring effect. The ratio of the radii of the superiorscallop to the inferior scallop in this preferred embodiment is two toone. The result is to create two curved and flat (in cross-section)sections, one on each side of the platform and these two flat sectionsin this preferred embodiment have about the same uniform thickness.Again, in this embodiment, the scallops and the platform is formed intoan otherwise uniformly diametered cylindrical rod. Accordingly, none ofthese formed elements in this preferred embodiment extend beyond thediameter of the rod. In this preferred embodiment, the diameter of thehorizontal rod is about 4 mm.

If desired, the rod could be bent in such a way that the platform and/orthe scallops extend outside of the diameter of the cylindrical rod.However that configuration would not be as suitable for implantationthrough a cannula or percutaneously as would the horizontal rod as shownin FIG. 33 and described above.

It is to be understood that to have enhanced flexibility, that thetorsion rod and connector elements used in the horizontal rod embodimentof FIG. 1 can be used with the horizontal rod of FIG. 33. In thisembodiment (FIG. 47), the connector is secured to the platform of thehorizontal rod of FIG. 33 with the two deflection rods or loading rodsextending toward the ends of the horizontal rod of FIG. 33 and aboutparallel to that horizontal rod.

Another embodiment of the horizontal rod 433 is depicted in FIG. 33A. Inthis embodiment the horizontal rod 433 is similar to the horizontal rodin FIG. 33 with the exception that the platform and scallops arereplaced with a reduced diameter central potion 448. Each end of thecentral portion 448 gradually increases in diameter until the diameteris the full diameter of the ends of the horizontal rod 433. Thisembodiment can be formed of a super elastic material and ground to thereduced diameter shape from a rod stock of the super elastic material.The rod stock could also be drawn to this shape. Generally after suchoperations the horizontal rod would be electro polished. In thisembodiment, a connector such as the connector shown in FIG. 40 could beused to connect vertical rods to preferably the middle of the centralportion 448.

FIGS. 34A, 34B, 34C depict yet an alternative embodiment of a horizontalrod 280 such as horizontal rod 116 as shown in FIG. 1 that is meant torigidly hold the vertical rods secured thereto. The mounts 282, 284formed in this horizontal rod 280 include a body that can be formed withthe rod 280. The mounts are then provided with a movable capture arm286, 288 that have recesses, which capture arms are formed out of themount preferably using a wire EDM process that leaves the capture armstill connected to the horizontal rod with a living hinge. Eccentricheaded set screws 290, 292 are mounted on the horizontal bar. Withvertical rods captured in the recesses of the capture arms, theeccentric set screws can be turned to urge the capture arms against theliving hinge, and thereby capturing the vertical rods in the recesses ofthe capture arms.

FIG. 40 depicts a dynamic stabilization system 450 that uses thehorizontal rod system 454 of the invention. The system 450 additionallyuses the anchor system 102 as depicted in FIG. 1 and the otherhorizontal rod 310 as depicted in FIGS. 19, 34. A connector 452 issecured to the platform 434 of the horizontal rod 454 and vertical rodsare connected to the connector and to the other horizontal rod 310. InFIG. 40 for the horizontal rod 454, the scallops are formed by bending abar and not by forming the scallops in a straight horizontal bar asdepicted in the horizontal bar 432 of FIG. 33. The horizontal rod 430 ofFIG. 33 could also be used in the embodiment of FIG. 40.

FIG. 35 depicts an alternative embodiment of a horizontal rod system 460of the invention. Horizontal rod system 460 includes a horizontal rod462 with a central platform 464 and first and second spring regions 466,468 located on either side of the platform 464. Extending outwardly fromeach spring region are respective ends of the horizontal rod 462. Thespring regions include coils that are wound about the longitudinal axisof the horizontal rod 462. If desired, the entire horizontal rod 462 canbe comprised of a rod wound around a longitudinal axis with the platform464 and the ends of the horizontal rod being more tightly wound and/orwith a smaller diameter and the spring regions 466, 468 more looselywound and/or with a larger diameter. Such a horizontal rod 462 canpreferably be comprised of super elastic material such as Nitinol oralternatively titanium or other biocompatible material whichdemonstrates the ability to flex repeatedly.

FIG. 36 depicts yet another alternative embodiment of a horizontal rodsystem 480 which includes first and second horizontal rods 482, 484which can be flat rods if desired. The horizontal rods 482, 484, includespring region 494, 496. In the spring region the horizontal rod isformed into an arc, much like a leaf spring. Located at the ends and atthe central platform 486 and between the horizontal rods 482, 484 arespacers 488, 490, 492. The spacers are glued, bonded, welded orotherwise secured between the first and second horizontal rods 482, 484in order to form the horizontal rod system 480. This system 480 can becomprised of super elastic materials or other materials that arebiocompatible with the patient.

FIG. 37 depicts another embodiment of the horizontal rod system 500including a horizontal rod 502. In this embodiment, recesses 504 areformed in the horizontal rod in order to define the stiffness of thehorizontal rod 502. This system can be formed of a super elasticmaterial or other biocompatible material.

FIG. 38 depicts still another embodiment of the horizontal rod system520 of the invention with a horizontal rod 522. The horizontal rod 522includes dimples 524 distributed around and along the horizontal rod522. As this other embodiment, depending on the distribution of thedimples, the stiffness of the horizontal rod 522 can be determined.Further is more dimples are placed on the lower surface than on theupper surface, when placed in a patient, the horizontal rod 522 wouldtend to be stiffer in extension and less stiff in flexion. Thishorizontal rod 522 can also be made of a super elastic material or otherbiocompatible material.

FIG. 39 depicts another embodiment of the horizontal rod system 530 ofthe invention which has a horizontal rod 532 which is similar to thehorizontal rod 432 of FIG. 33 and, thus, similar elements will numberwith similar numbers. In addition, the ends 534, 536 of the horizontalrod 532 are curved so as to create hooks that can fit around portions ofthe vertebra so as to secure the horizontal rod 532 to the vertebra. Inthis embodiment, preferably the rod is comprised of super elasticmaterial or other biocompatible material. In order to implant the rod,the hooks at ends 534, 536 are sprung open and allowed to spring closedaround the vertebra. An anchor system which includes a hook (asdiscussed above) could be used with this system.

FIGS. 39A, 39B are similar to FIG. 39. In FIGS. 39A, 39B, a horizontalrod 532 is held in place relative to the spine by two anchor systems102. The anchor systems are similar to the anchor systems depicted inFIG. 1. The anchor systems 102 include an anchor or bone screw 108 orbone hook 109 with spikes 111 (FIG. 39B), as well as the head 110 intowhich the horizontal rod is received. A set screw 112 secures thehorizontal rod relative to the anchor systems.

FIG. 41 depicts another embodiment of the dynamic stabilization system540 of the invention. This embodiment includes side loading anchorsystems 542 as described above, although top loading anchor systemswould also be appropriate for this embodiment. In this embodiment thehorizontal rods 544, 546 are preferably comprised of a polymer such asPEEK and mounted on the horizontal rods 544, 546 are first and secondconnectors 548, 550. Vertical rods 552 and 554 are connected to thefirst and second connectors 548, 550 at points 556 with screws, rivetsor other devices so that the connection is rigid or, alternatively, sothat the vertical rods 552, 554 can pivot or rotate about the points. Asthe horizontal rods are comprised of PEEK, the system tends to be morerigid than if the rods were comprised of a super elastic material.Rigidity also depends on the diameter of the rod.

Embodiments of the Vertical Rod System of the Invention

Embodiments of vertical rod systems of the invention such as verticalrod system 106 are presented throughout this description of theinvention. Generally, the vertical rod systems are comprised of verticalrods that can be pivoted or inserted into position after the horizontalrods are deployed in the patient. The vertical rods are preferablyconnected to the horizontal rods and not to the anchor systems in orderto reduce the forces and stress on the anchor systems. The vertical rodsare connected to the horizontal rod systems, which horizontal rodsystems include mechanisms as described herein that reduce the forcesand stresses on the anchor systems. The vertical rods can generally becomprised of titanium, stainless steel, PEEK or other biocompatiblematerial. Should more flexibility be desired, the vertical rods can becomprised of a super elastic material.

Embodiments of Alternative Multi-Level Dynamic Stabilization Systems forthe Spine

FIGS. 42 and 43 depict multi-level dynamic stabilization systems 560,580. Each of these systems 560, 580 are two level systems. All of thesesystems use anchor systems as described herein. In system 560 of FIG. 42the middle level horizontal rod 562 is secured to a vertebra andincludes a horizontal rod system 104 having first and second deflectionrods or loading rods such as that depicted in FIG. 4, whereby a firstpair of vertical rods 564 can extend upwardly from horizontal rod systemand a second pair of vertical rods 566 can extend downwardly from thehorizontal rod system. The vertical rods that extend upwardly areconnected to an upper horizontal rod 568 such as depicted in FIG. 34 andthe vertical rods that extend downward are connected to a lowerhorizontal rod 568 such as depicted in FIG. 34. The upper horizontal rod568 is secured with anchor systems to a vertebra located above thevertebra to which the middle level horizontal rod 562 is secured. Thelower horizontal rod 570 is secured with anchor systems to a vertebralocated below the vertebra to which the middle level horizontal rod 562is secured. This embodiment offers more stability for the middle levelvertebra relative to the upper and lower vertebra while allowing forextension, flexion, rotation and bending relative to the middle levelvertebra.

FIG. 43 depicts another multi-level dynamic stabilization system 580.All of these systems use anchor systems as described herein. In system580 of FIG. 43, the middle level horizontal rod 582 is secured to avertebra and includes a horizontal rod such as that depicted in FIG. 34.The upper and lower horizontal rods 586, 590 can be similar to thehorizontal rod 114 including the deflection rods or loading rods anddeflection rod or loading rod mount depicted in FIG. 3. Vertical rodsare pivotally and rotationally mounted to the upper and lower horizontalrods 586, 590 and, respectively, to the deflection or loading rodsthereof and are also rigidly mounted to the middle level horizontal rod582. The upper horizontal rod 586 is secured with anchor systems to avertebra located above the vertebra to which the middle level horizontalrod 582 is secured. The lower horizontal rod 590 is secured with anchorsystems to a vertebra located below the vertebra to which the middlelevel horizontal rod 582 is secured. This embodiment offers more dynamicstability for the upper and lower vertebra relative to the middle levelvertebra while allowing for extension, flexion, rotation and bendingrelative to the middle level vertebra. Alternatively, the middle levelhorizontal rod 582 has four mounts instead of the two mounts depicted inFIG. 34 or FIG. 34A so that a first pair of vertical rods 588 can extendupwardly from a lower horizontal rod 590 and a second pair of verticalrods 566 extending downwardly from the upper horizontal rod 586, can besecured to the middle level horizontal rod 582.

Embodiments of Spine Fusion Systems of the Invention

FIGS. 44, 45 depict one and two level systems that are more preferablyused for fusion. The system 600 depicted in FIG. 44 resembles the systemdepicted in FIG. 41. When PEEK is used for the horizontal rods 602, 604,the system is substantially rigid and can be used in conjunction withspine fusion. For example, this system can be used with the placement ofbone or a fusion cage between vertebra to which this system is attached.In fusion, bone can be placed between the vertebral bodies or,alternatively, fusion can be accomplished by placing bone in the valleyson each side of the spinous processes. The horizontal rods 602, 604 analso be comprised of titanium, or other biocompatible material and beused for spine fusion. For this embodiment, the vertical rods 606 can berigidly attached to the horizontal rods through the use of a horizontalrod with mounts, as depicted in FIG. 34, so that the vertical rods 606do not move or pivot with respect to the horizontal rods.

FIG. 45 depicts a two level system 620 that is more preferably used fora two level fusion. Each level can use an anchor system for exampledescribed with respect to anchor system 102 of FIG. 1. The horizontalrods 622, 624, 626 are can be similar to the horizontal rod in FIG. 34with either two vertical rod mounts for the upper and lower horizontalrods 622, 626 or four vertical rod mounts for the middle levelhorizontal rod 624. For this embodiment, the vertical rods 628, 630 canbe rigidly attached to the horizontal rods through the use of ahorizontal rod with mounts as depicted in FIG. 34 so that the verticalrods 628, 630 do not move or pivot with respect to the horizontal rods.Vertical rods 628 extend between the upper and middle horizontal rods622, 624, and vertical rods 630 extend between the middle and lowerhorizontal rods 624, 626. The system 620 depicted in FIG. 44 resemblesthe system depicted in FIG. 41, but with respect to three levels. WhenPEEK is used for the horizontal rods 622, 624, 626, the system issubstantially rigid and can be used in conjunction with spine fusion.For example, this system can be used with the placement of bone or afusion cage between vertebra to which this system is attached. Bone canalso be placed along the valleys on either side of the spinous processesfor this system. The horizontal rods 622, 624, 626 can also be comprisedof titanium, PEEK or other biocompatible material and be used for spinefusion.

With respect to FIG. 45, to ease the transition to a one level fusedarea of the spine this two level system can be modified by replacing thehorizontal rod 622 with a horizontal rod 115 (FIGS. 45A, 45B), which ismuch like horizontal rod 104 with deflection or loading rods 118, 120 ofFIG. 1. This embodiment is depicted in FIG. 45A. Thus, fusion isaccomplished between the two lower horizontal rods 117 which rods arelike those depicted in FIG. 34, or like horizontal rods 116 in FIG. 1,and made of, preferably, titanium, and flexibility is provided by theupper horizontal rod 115 that is like horizontal rod 114 with deflectionor loading rods that are shown in FIG. 1. Accordingly, there is moregradual transition from a healthier portion of the spine located abovehorizontal rod 115 through horizontal rod 115 to the fused part of thespine located between horizontal rod 624 and horizontal rod 606 of FIG.45 or between the horizontal rods 117 (FIG. 45A).

Further Embodiments of the Dynamic Stabilization System And Embodimentsof the Connectors, the Horizontal Rod System, and the Vertical RodSystem

Various embodiments of the dynamic stabilization system have been shownand described above. FIGS. 48-85 provide further embodiments of thedynamic stabilization system. Referring now to FIGS. 48 and 49,perspective and posterior views of another embodiment of a dynamicstabilization system 700 can be seen. Generally, as with the embodimentsdescribed above, the dynamic stabilization system 700 includes an anchorsystem 702, a horizontal rod system 704 and a vertical rod system 706.For these embodiments horizontal refers to a horizontal orientation withrespect to a human patient that is standing and vertical refers to avertical orientation with respect to a patient that is standing. Thehorizontal rod system 704 can include a first horizontal rod 708, asecond horizontal rod 710 and a deflection rod system 712. The verticalrod system 706 can include vertical rods 716 which are used withseparate connectors 718 to attach the vertical rods 716 to thedeflection rod system 712 attached to the first horizontal rod 708 andcan use connector 1210 to attach vertical rods 716 to the secondhorizontal rod 710.

As shown in FIGS. 48-49, the deflection rod system 712 is attached, inthis embodiment, to the center of the first horizontal rod 708 within amount 714, while being connected to the vertical rods 716 at the ends722, 724 of the deflection rod system 712. The deflection rod system 712is positioned about parallel to the first horizontal rod 708, the firsthorizontal rod 708 being attached to the anchor systems 702 and, inparticular, to the heads or saddles of the anchor system 702.Preferably, the horizontal rods 708, 710 are stiff and rigid (and madeof titanium, for example), particularly in comparison to the deflectionrod system 712 (which can be made of a super elastic material such asNitinol (inner deflection rod 720 (FIG. 50A) and a polymer such as PEEK(outer shell 721), for example). In this configuration, the horizontalrod system 704 and, in particular, the deflection rod system 712 sharesand distributes the load resulting from the motions of the body of thepatient. Various embodiments of the vertical rods 716, the connectors718, 1210, the deflection rod system 712, and the horizontal rods 708,710 can be utilized as a part of the dynamic stabilization system 700 aswill be described in greater detail below.

FIGS. 50A-55B illustrate an embodiment of a deflection rod system 712, avertical rod 716 and a connector 718 used within the dynamicstabilization system 700. Referring now to FIGS. 50A-55B, the deflectionrod system 712 includes an inner deflection rod 720 having a first end722 and a second end 724, a retaining ring 726 and a spherical ball orjoint 728. As will be further described with regard to FIGS. 68-71, thedeflection rod system 712 includes an inner rod 720 preferably made of,for example, a super elastic material such as Nitinol, and an outershell 721 made of a polymer such as PEEK. In this embodiment, the firstend 722 of the inner deflection rod 720 of the deflection rod system 712can be passed through the retaining ring 726 and attached to thespherical ball or joint 728 (as shown in FIG. 51) using threading,fusing, gluing, press fit and/or laser welding techniques, for example.In this embodiment, the spherical ball or joint 728 is only connected tothe deflection rod 720 and not to the outer shell 721 of the deflectionrod system 712. The spherical joint 728 can then be positioned withinthe socket chamber 768 of the connector 718. Once the spherical joint728 is positioned within the connector 718, the retaining ring 726 canbe threaded, fused, glued, press fit and/or laser welded, for example,to the connector 718, thereby securing the deflection rod 712 to theconnector 718 (as shown in FIG. 52) in a ball joint type connection. Inthis configuration, the deflection rod system 712 is allowed to rotateand/or have tilting and/or swiveling movements about a center whichcorresponds with the center of the spherical ball or joint 728.

Referring to FIGS. 51 and 52, the vertical rod 716 used in thisembodiment of the dynamic stabilization system 700 includes a head 730having an aperture 732 that can accept a screw 734 and a rectangularshell or recess 736 for accepting the connector 718. Turningadditionally to FIGS. 53 and 54, the aperture 732 of the vertical rod716 includes a first bore 738 and a second bore 740. The first bore 738of the aperture 732 can be configured to encase the head 742 of theconnector screw 734 while the second section 740 can be configured tocapture the neck 735 of the screw 734. Accordingly, the first section738 of the aperture 732 has a larger diameter than the second bore 740of the aperture 732, the overall shape of the aperture 732 conforming tothe shape of the connector screw 734.

Referring back to FIG. 52, the rectangular shell or recess 736 of thevertical rod head 730 is configured to fixedly receive and encase theconnector 718. Accordingly, the inner surface of the rectangular shellor recess 736 includes a top surface 746, inner side surfaces 748, 750,and inner front and back surfaces 752, 754. In this embodiment, the top746, front 752 and back 754 inner surfaces are flat and rectangular inshape, while the inner sides surfaces 748, 750 are flat with asaddle-shaped cut-out which can allow for movement of the deflection rodsystem 712 and/or the vertical rod 716 relative to each other. Also inthis embodiment, the bottom surface 756 of the head 730 is elevated fromthe bottom surface 758 of the vertical rod shaft 760 in order to providea space for the connector 718 to be attached to the bottom of the head730. The extent of elevation can vary depending on the size of theconnector 718 attached thereto.

Referring back to FIG. 51, the connector 718 used in this embodiment ofthe dynamic stabilization system 700 includes a threaded aperture 762for accepting the connector screw 734 and a housing 764 for acceptingthe deflection rod system 712. In its deployed position, the aperture762 within the connector 718 is lined up with and placed adjacent to theaperture 732 located on the vertical rod 716, the connector screw 734being inserted into both apertures 732, 762 to secure the connector 718to the vertical rod 716.

FIGS. 51 and 52 further illustrates the housing 764 of the connector 718as having a generally cylindrical exterior surface 765 with a flat topsurface 766. The housing 764 also includes an opening 770 on the frontface 772 of the connector 718 leading to a socket or spherical chamber768 formed within the housing 764. The socket or spherical chamber 768can be configured to engage the spherical ball or joint 728 of thedeflection rod system 712. In this configuration, the spherical ball orjoint 728 of the deflection rod system 712 is allowed to be pivotallyengaged to the connector 718 within the socket or spherical chamber 768while the deflection rod 720 is allowed to extend away from theconnector 718 through the opening 770 of the front face 772 of thehousing 764. The retaining ring 726 holds the ball 728 in place in theconnector 718.

Referring back to FIG. 52, as the aperture 732 in the vertical rod 716is aligned with the aperture 762 in the connector 718, the vertical rodrecess or shell 736 can also be aligned with the housing 764 of theconnector 718. The connector housing 764 can be inserted into thevertical rod recess or shell 736 until the connector housing 764 engagesthe top 750 and sides 748, 750, 752, 754 along the inner surface of thevertical rod shell 736. In this configuration, movement of the connector718 within the head 730 of the vertical rod 716 is minimized and/oreliminated. This configuration also allows the vertical rod shell 736 toabsorb any pressure resulting from movements of the deflection rodsystem 712 and vertical rod 716 during use, thereby limiting thepressure placed on the screw 734 during use.

FIG. 55A further illustrates the connection between the deflection rodsystem 712, the connector 718 and the vertical rod 716 in thisembodiment. As can be seen in FIG. 55A, the retainer ring 726 has anouter diameter which is slightly smaller than the diameter of theopening 770 on the front face 772 of the connector 718. The retainerring 726 has a flat front surface 774, while the inner surface of theretaining ring 726 includes a curved section 776, the radius ofcurvature for the curved section 776 being the same as the radius ofcurvature of the spherical ball or joint 728. Accordingly, the retainingring 726 can be inserted into the opening 770 through the front face 772of the connector 718 until it is in sliding engagement with thespherical joint ball or 728. The connector 718 can also include a ridge778 on its inner surface which limits the depth of insertion of theretainer ring 726 into the connector 718. The retainer ring 726 can thenbe screwed, fused, glued, force fit, and/or laser welded to theconnector 718.

FIG. 55B illustrates an alternative fastening technique. In thisembodiment, the spherical ball or joint 728 is inserted into theconnector 718 through an opening 780 on the back face 780 of theconnector 718 while the deflection rod 720 is inserted into theconnector 718 through an opening 770 on the front face 772 of theconnector 718. Once the parts have been inserted, the spherical joint728 and the deflection rod 720 are connected within the connector 718.Alternatively, the spherical ball or joint 728 and the deflection rod720 can be preassembled by, for example, screwing, gluing, force fittingand/or laser welding before the spherical joint 728 is placed in theconnector 718. A retainer ring 726 can then be used to prevent thespherical joint 728 from exiting the connector 718 through the opening780 on the back face 782 of the connector 718. The retainer ring 726 maybe screwed, fused, glued, force fit and/or laser welded to the connector718. Other fastening techniques are also within the scope and spirit ofthe invention.

Once the deflection rod system 712 is secured to the connector 718, theconnector 718 can then be secured to the vertical rod 716 as shown inFIG. 53. In this configuration, the connector 718 is mated with the head730 of the vertical rod 716. When mating the connector 718 to the head730 of the vertical rod 716, the aperture 732 in the vertical rod 716 isaligned with the aperture 762 of the connector 718. The connector screw734 then can secure the vertical rod 716 to the connector 718.

FIGS. 56A-59 illustrate another embodiment of a deflection rod system800, a vertical rod 802 and a connector 804 that can be used within thedynamic stabilization system 700. In this embodiment, acylindrically-shaped connector 804 including a U-shaped slot 810 is usedto attach the vertical rod 802 to the deflection rod system 800 as willbe described in greater detail below.

Referring now to FIGS. 56A and 56B, the connector 804 in this embodimentis shown as including a cylindrical body 806 having an internalcylindrical bore 808, a U-shaped slot 810 and a lock tab 812. Thedeflection rod system 800 in this embodiment includes a deflection rod814 (preferably made of Nitinol, Niti or other super elastic material)having an outer shell 815 (preferably made of PEEK or other comparablepolymer) and a spherical ball or joint 816. The connector 804 includes asocket chamber 818 which is formed within the U-shaped slot 810 forreceiving the spherical ball or joint 816 of the deflection rod system800. Once the spherical ball or joint 816 of the deflection rod system800 is positioned within the socket chamber 818, the exterior panel 820of the lock tab 812 can be moved from its open, undeployed configuration(as shown in FIG. 56A) to its closed, deployed configuration (as shownin FIG. 56B), thereby closing the opening of the U-shaped slot 810around the spherical ball or joint 816 of the deflection rod system 800to secure the deflection rod system 800 to the connector 804. Thespecific mechanism employed to move the exterior panel 820 of the locktab 812 in this embodiment of the invention is illustrated in FIG. 59,which is described in greater detail below. In the deployedconfiguration of the connector 804, the deflection rod system 800 ispivotally engaged to the connector 804 within the socket chamber 818while the deflection rod shaft 814 extends away from the connector 804.Consequently, the vertical rod 802 is allowed to rotate and/or havetilting and/or swiveling movements about a center that corresponds withthe center of the spherical joint 816.

FIG. 57 illustrates the vertical rod 802 used in this embodiment of theinvention. The vertical rod 802 includes a vertical rod shaft 822, athreaded band 824, and an end cap 826 having a cavity 828 for acceptingthe lock tab 812 of the connector 804. In this embodiment, the threadedband 824 and the end cap 826 are both located adjacent to the first end830 of the vertical rod shaft 822. The diameter of the threaded band 824can be greater than the diameter of the vertical rod shaft 822 and theend cap 826. In an embodiment, the vertical rod 802 may not include anend cap 826 at all, in which case the threaded band 824 will include acavity for accepting the lock tab 814 of the connector 804.

FIG. 58 provides a detailed illustration of the lock tab 812 used inthis embodiment of the invention. The lock tab 812 includes the exteriorpanel 820, a cylindrical platform 832 and a knob 834. In thisembodiment, the exterior panel 820 can include a convex outer surface836 and a concave inner surface 838. The cylindrical platform 832 islocated along the inner surface 838 of the exterior panel 820, the topsurface 840 of the cylindrical platform 832 being parallel to the topsurface 842 of the exterior panel 820. The knob 834 is centrally locatedalong the top surface 842 of the cylindrical platform 832. In use withinthe connector 804, the knob 834 can be used to fasten the lock tab 812to the vertical rod 802, whereby the inner surface 838 of the exteriorpanel 820 and the knob 834 both conform to the shape of the end cap 826of the vertical rod 802 as shown in FIG. 59. In order to secure the knob834 to the vertical rod 802 the knob 834 includes a cylindrical base 844having a bevel-shaped collar 846 and a U-shaped slit 848. As the knob834 is inserted into the cavity 828 within the end cap 826 of thevertical rod 802, the U-shaped slit 848 allows the ends 850 of the knob834 to pinch in until the collar 846 extends past the top of the end cap826 of the hollow vertical rod 802. Once the collar 846 extends past thetop of the end cap 826, the collar 846 catches under lip 84 and returnsto its original unpinched configuration, thereby securing the verticalrod 802 to the lock tab 812 (as shown in FIG. 59).

Referring to FIG. 59, a cross-sectional view of the deflection rodsystem 800 and the vertical rod 802 within the connector 804 can beseen. The connector 804 has an internal cylindrical bore 808 foraccepting the vertical rod 802 which is positioned substantiallyparallel to the longitudinal axis of the cylindrical body 806. Theinterior surface of the cylindrical body 806 includes threads 852 forengaging the threaded band 824 of the vertical rod 802. In thisembodiment, the vertical rod 802 can be screwed into the cylindricalbody 806 until the end cap 826 of the vertical rod 802 is placed insliding engagement with the lock tab 812 knob 834. Engagement of thevertical rod 802 to the lock tab 812 is accomplished, as set forthabove, by inserting the knob 834 into the cavity 828 of the end cap 826of the vertical rod 802 until the collar 846 of the knob 834 extendspast the lip 847 of the end cap 826, whereby the collar 846 of the knob834 secures the vertical rod 802 to the lock tab 812. In thisconfiguration, the end cap 826 of the vertical rod 802 is free to rotatearound the knob 834 of the lock tab 812 while the vertical rod 802remains engaged to the lock tab 812. Once the vertical rod 802 is placedin engagement with the lock tab 812, the lock tab 812 can be moved upand down by way of threaded movement of the vertical rod 802 within thecylindrical body 806 of the connector 804. In the deployed configurationof the connector 804, the spherical ball or joint 816 of the deflectionrod system 800 is inserted into the U-shaped slot 810 of the connector.Once the ball 816 of the deflection rod system 800 is positionedtherein, the exterior panel 820 and the locking tab 812 can be moveddown to block the opening of the U-shaped slot 810 of the connector 804.In an embodiment, the lower inner surface 854 of the lock tab 812 can beconcave and rounded to engage the spherical ball or joint 816 of thedeflection rod system 800.

FIGS. 60-64 illustrate another embodiment of the deflection rod system900, the vertical rod 902 and the connector 904 used within the dynamicstabilization system 700. As shown in FIG. 60, the deflection rod system900 used in this embodiment includes a deflection rod 906 having anouter shell 907, the deflection rod 900 further including spool-shapedend caps 908 attached thereto, having circumferential retaining ridges915, attached to the ends of the end cap 908. The end cap 908 can bescrewed, glued, force fit, fused and/or laser welded onto the deflectionrod 906. In this embodiment, the spool-shaped cap 908 is not connectedto the shell 907. Instead, the shell 907 extends along the rod 906 andis short of the end cap 908. As with other embodiments, the deflectionrod 906 can be comprised of a super elastic material and the shell 907can be comprised of a polymer such as PEEK. The shell 907 protects therod 906 and adds rigidity to the deflection rod system 900, and the rod906 includes the deflection and recovery properties of a super elasticmaterial. One of ordinary skill in the art can appreciate that otherembodiments of the deflection rod system 900, such as the onesillustrated in FIGS. 68-71 or any other embodiments described herein,can be used in this embodiment of the dynamic stabilization system 700without deviating from the scope of this invention.

FIG. 60 illustrates the connector 904 used in an embodiment of theinvention. The connector 904 can be seen as including a C-shaped slot910 for accepting the spool-shaped end cap 908 of the deflection rodsystem 900 and a sliding tab 912 which can close the opening of theC-shaped slot 910 to secure the spool-shaped end cap 908 of thedeflection rod system 900 to the connector 904.

Referring now to FIG. 61, a detailed illustration of this embodiment ofthe connector 904 is provided. The connector 904 can be seen asincluding the C-shaped slot 910 including two channels 914 adjacent tothe side surfaces 916 of the connector 904. The channels 914 allow theC-shaped slot 910 to conform to the shape of the end cap 908 of thedeflection rod system 900 (as shown in FIG. 60) and receives thecircumferential retaining ridges 915 of the end cap 908. Thisconfiguration defines the movement of the deflection rod 900 within theconnector 904. The connector 904 further includes L-shaped tabrestraints 918 having a pair of grooves 920 along the inner surface ofthe tab restraints 918 as well as a groove 922 along the lower innersurface of the C-shaped slot 910. The L-shaped tab restraints 918 andvarious grooves 920, 922 facilitate securing the sliding tab 912 to theconnector 904 as will be described in greater detail below.

Referring now to FIG. 62A and FIG. 62B, the embodiment of the slidingtab 912 shown in FIG. 60 is illustrated in greater detail. The slidingtab 912 of this embodiment includes a first end 924 and a second end926. The sliding tab 912 further including a U-shaped slot 928 at end924, side knobs 930, a bottom lip 932 at end 926 and a rear restraint934. The U-shaped slot 928, located adjacent to the first end 924 of thesliding tab 912, is positioned parallel to the longitudinal axis of thesliding tab 912. The U-shaped slot 928 allows the first end 924 of thesliding tab 912 to pinch together within the L-shaped tab restraints 918of the connector 904 (shown in FIG. 61) as the sliding tab 912 is beingplaced in its deployed position. The side knobs 930 are located on theside surfaces 936 of the sliding tab 912 and conform to the grooves 920along the inner surface of the tab restraints 918 of the connector 904(shown in FIG. 61). The bottom lip 932, located adjacent to the secondend 924 of the sliding tab 912, conforms to and can be received in thegroove 922 along the lower inner surface of the C-shaped slot 910 of theconnector 904 (shown in FIG. 61). Referring to FIG. 62B, the backsurface 938 of the sliding tab 912 can be seen as including a curvedsection 940 which can be configured to conform to the cylindrical shapeof the spool-shaped end cap 908. The back surface 938 of the sliding tab912 can also include the rear restraint 934. In this embodiment, therear restraint 934 can be inserted into a slot 948 within the verticalrod 902 (shown in FIG. 64) to position the vertical rod 902 relative tothe connector 904 for deployment into a patient. The side knobs 930 andthe bottom lip 932 also facilitate securing the sliding tab 912 to theconnector 904 (as shown in FIG. 63).

FIG. 63 illustrates the connector 904 in its deployed configuration. Asshown, the deflection rod system 900 is secured to the connector 904within the C-shaped slot 910 using the sliding tab 912. In thisconfiguration, the side knobs 930 are mated with the grooves 920 alongthe inner surface of the tab restraints 918 and the bottom lip 932 ismated with the groove 922 along the lower inner surface of the C-shapedslot 910, thereby locking the sliding tab 912 into its deployed positionwithin the connector 904 and locking the connector 904 about thespool-shaped end cap 904. Accordingly, the vertical rod can rotate aboutthe end cap 904 and thus rotate about the longitudinal axis of thetorsion rod system 900.

As shown in FIG. 64, the vertical rod 902 used in this embodiment of theinvention includes a vertical rod shaft 944, a first slot 946 foraccepting the connector 904 and a second slot 948 for accepting the rearrestraint 934 of the sliding tab 912. The vertical rod 902 also includesan aperture 950 for accepting a screw, rivet or pin. In this embodiment,the back of the connector 904 can be shaped to conform to the shape ofthe vertical rod 902. Accordingly, the vertical rod 902 can be matedwith the connector 904 as shown in FIG. 60, and a screw, rivet or pincan be inserted through the aperture 950 of the vertical rod 902 intothe connector 904 to secure the vertical rod 902 to the connector 904and/or allow the vertical rod 902 to pivot about the screw, rivet or pin(see arrows 905) and relative to the horizontal rod 900. The rearrestraint 934 can be held in the slot 948 prior to the sliding tab 912being lockingly deployed to capture the spool-shaped end cap 918 in theC-shaped slot 910.

FIGS. 65-67 illustrate yet another embodiment of the deflection rodsystem 1000, the vertical rod 1002 and the connector 1004 which can beused as a part of the dynamic stabilization system 700. Referring now toFIG. 65, the deflection rod system 1000 can be seen as including adeflection rod 1006 having spool-shaped end caps 1008 attached to theends of the shaft 1006 and shell 1007 similar to the embodiment depictedin FIG. 60. It is noted that one of ordinary skill in the art canappreciate that other embodiments of the deflection rod system 1000,such as the ones illustrated in FIGS. 68-71 or any other embodimentsdescribed herein, can be used in this embodiment of the dynamicstabilization system 700 without deviating from the scope of thisinvention.

FIG. 66 illustrates the connector 1004 of this embodiment of theinvention. The connector 1004 can be seen as having a U-shaped slot 1010on the first end 1012 of the connector 1004, and a clamp, generallynumbered 1014, on the second end 1016 of the connector 1004. TheU-shaped slot 1010 can be configured to accept the vertical rod 1002. Inan embodiment, the connector 1004 includes apertures 1018, 1020 alongthe sides of the U-shaped slot 1010 for accepting a pin or screw 1022.Once an aperture 1036 (FIG. 67) of the vertical rod 1002 is placedwithin the U-shaped slot 1010, the pin or screw 1022 can be insertedinto the apertures 1018, 1020 of the connector 1004 as well as thevertical rod 1002 to either fixedly or pivotally secure the vertical rod1002 to the connector 1004. The pin or screw 1022 can be fused, glued,screwed, force fit and/or laser welded to the connector 1004.

The clamp 1014 includes a C-shaped arm 1024 as well as a C-shapedlocking paw 1026 that is pivotally attached to the connector 1004 usinga pivot pin 1028. The clamp 1014 also includes a clamp set screw 1030which can adjust the position of the locking paw 1026. In thisembodiment, the end cap 1008 of the deflection rod 1000 can be securedto the connector 1004 between the C-shaped arm 1024 and the locking paw1026 in the closed configuration of the clamp 1014 as shown in FIG. 65and held in place by set screw 1030. Accordingly, the vertical rod canpivot about the deflection rod 1006 with the end cap 1008 retained inthe clamp 1014.

Referring now to FIG. 67, the vertical rod 1002 used in this embodimentof the invention can be seen as including a cylindrical shaft 1032, ahead 1034 having an aperture 1036 for accepting a pin or screw, and aspacer 1038 located between the head 1034 and the shaft 1032. In thisembodiment, the head 1034 of the vertical rod 1002 conforms to theU-shaped slot 1010 of the connector 1004.

Alternate Embodiments of the Deflection Rod System and the FirstHorizontal Rod of the Invention

FIGS. 68-71 illustrate another embodiment of deflection rod system 1100which can be used within the embodiments of the dynamic stabilizationsystems 700 described herein. The deflection rod system 1100 generallyincludes a deflection rod 1108 and two end caps 1104. The end cap 1104can be, for example, spool-shaped or spherically-shaped as illustratedwith respect to other embodiments. The deflection rod system 1100 canalso include an outer shell 1106. In an embodiment, the deflection rod1108 is cylindrical and made of a super elastic material, preferablyNitinol (NiTi). The diameter of the deflection rod 1108 is constant inthis embodiment. In this embodiment, the outer shell 1106 of thedeflection rod system 1100 is made of a biocompatible material orpolymer, preferably PEEK, which is less elastic than the deflection rod1108. In this embodiment, the deflection rod shell 1106 includes ahollow tube which is generally tapered. The tube increases in diameterfrom the ends 1118 of the shell 1106 to the central portion 1110 of theouter shell 1106. A channel 1112 can be provided at the central portionof the shell 1106 to facilitate the retention of the deflection rodsystem 1100 in a mount on a horizontal rod such as, for example, mount714 on horizontal rod 708 in FIG. 45. Instead of a channel 1112, aring-shaped plateau or land can be defined having the largest diameterof the shell 1106 (FIG. 70). Either the channel 1112 or the plateau canbe received in the mount 714 of the horizontal rod system as seen inFIG. 48. In an embodiment, the end caps 1104 can be made of titanium,stainless steel, a biocompatible polymer such as PEEK or anotherbiocompatible material. In this embodiment, the end caps 1104 are spoolshaped or cylindrical shaped and include a central channel 1114.

The deflection rod 1108 can be inserted into the outer shell 1106 of thedeflection rod system 1100 so that the ends 1116 of the deflection rod1108 extend past from the ends 1118 of the outer shell 1106. The endcaps 1104 can then be attached to the end 1116 of the deflection rod1108. The purpose of the deflection rod shell 1106 is to protect thedeflection rod 1108, which is made of the super elastic material and tosupport and restrict the motion of the rod 1108. The outer shell 1106also serves to reduce the strain on the deflection rod 1108 as force isapplied to the ends 1116 of the deflection rod 1108. As increased strainis placed on the ends 1116 of the deflection rod 1108, and spread alongthe entire length of the deflection rod 1108, the deflection rod shell1106 can resist such strain along the entire length of the shell 1106.The outer shell 1106 of the deflection rod system 1100 helps to limitthe maximum amount of deflection allowed by the deflection rod system1100 as well as support and protect the deflection rod 1108.

FIGS. 70 and 71 illustrate other embodiments of the deflection rodsystem 1100. Referring first to FIG. 70, this embodiment of thedeflection rod system 1100 is similar to the deflection rod system 1100embodied in FIG. 68. However, in this embodiment, the central portion ofthe deflection rod shell 1106 includes a central ring or plateau 1120 asopposed to a channel. Referring now to FIG. 71, this embodiment of thedeflection rod system 1100 includes a deflection rod shaft 1122 having aconstant diameter and two end caps 1124 also having constant diameters.As can be seen in FIG. 71, the diameter of the deflection rod shaft 1122is larger than the diameter of the end caps 1124. It is noted that aswith the deflection rod system 1100 illustrated in FIGS. 68 and 69, theembodiments of the deflection rod systems illustrated in FIGS. 70-71include a deflection rod or core 1108 and a deflection rod shell 1106 asdescribed above. The embodiments illustrated in FIGS. 68-71 are notintended to be limiting and it is envisioned that the deflection rodsystem 1100 may include other embodiments which would be evident to oneskilled in the art without deviating from the scope of the invention.

FIGS. 72A-73C illustrate alternative embodiments of the first horizontalrod 708. Referring now to FIG. 72A, an embodiment of the firsthorizontal rod 708 is shown as including a mount 714, a pair of guide ordeflection restraining rings 1200 and a pair of grooves 1202 proximal toand outboard of the guide rings 1200. In this embodiment, the deflectionrod system 712 is secured to the first horizontal rod 708 within themount 714. The deflection rod system 712 is further contained within theguide rings 1200 proximal to the ends of the deflection rod system 712.The guide rings 1200 can be used to limit the amount of deflection ofthe deflection rod system 712 in use as well as to prevent thedeflection rod system 712 from becoming overextended during use. In thisembodiment, the guide rings 1200 are elliptical rings wherein thevertical diameters of the guide rings 1200 are greater than thehorizontal diameters of the guide rings (FIG. 72C). Again, horizontalreferring to a horizontal orientation with respect to a patient that isstanding and vertical referring to a vertical orientation with respectto a patient that is standing. The configuration of the guide ring 1200allows the deflection rod system 712 to have a greater amount ofvertical deflection than horizontal deflection. It is envisioned thatthe guide rings 1200 can have other configurations and still fall withinthe scope of this invention.

The first horizontal rod 708 also includes the grooves 1202 which can bemated with corresponding knobs 1204 located on the end caps 1206 of avertical rods 716 to keep the ends caps 1206 and/or the vertical rods716 aligned during deployment into the patient. Alternatively, suchinitial alignment technique can be dispensed with. In this embodiment,the vertical rod 716 includes an end cap 1206 and a main vertical shaft1208 wherein the main vertical shaft 1208 can be screwed into the endcap 1206. It is to be understood that the horizontal system can first beinserted into a patient without the main vertical shaft 1208 beingattached (as shown in FIG. 72B). Once the horizontal system hassuccessfully been inserted, the main vertical shafts 1208 can beattached to the end caps 1206, wherein the grooves 1202 and the knobs1204 can act to align and steady the end caps 1206 as the main verticalshafts 1208 are inserted into the end caps 1206 (as shown in FIG. 72C).

Referring now to FIGS. 73A-73C, another embodiment of the firsthorizontal rod is illustrated. As can be seen in FIGS. 73A and 73B, thefirst horizontal rod 708 of this embodiments includes a deflection rodcollar or shield 1210 that wraps around the deflection rod system 1100.The deflection rod shield 1210 is preferably stiff and rigid (and madeof titanium, for example). The deflection rod shield 1210 can be used toprotect the deflection rod 712 from damage during use. The deflectionrod system 1100 includes a rod 1108 and an outer shell 1106 as shown forthe deflection rod system 1100 in FIG. 69. The deflection rod shield1210 can also be used to limit the amount of deflection of thedeflection rod system 1100 as well as prevent the deflection rod system1100 from becoming overextended during use. Referring now to FIG. 73C,the inner surface 1212 of the deflection rod shield 1210 can be seen asbeing tapered wherein the diameter of the inner surface 1212 of thedeflection rod shield 1210 is greater at the ends 1214, 1216 than at thecenter 1218 of the deflection rod shield 1210. In this configuration,the surface of the deflection rod system 1100 can touch the innersurface 1212 of the deflection rod shield 1210 during use. Accordingly,the deflection rod shell 1210 can limit the movement of the deflectionrod system 1100 and assist in spreading the load and strain on thedeflection rod system 1100 along the entire length of the deflection rodsystem 1100. Also in this embodiment, the first horizontal rod 708includes a cavity 1220 to encompass the deflection rod system 1100within the deflection rod shield 1210 to give the first horizontal rod708 a smaller profile when implanted into a patient. It is envisionedthat the deflection rod system 1100 can be mounted to any other type ofhorizontal rod which would be obvious to one skilled in the art withoutdeviating from the scope of the invention.

Alternative Embodiments for Connections Used to Mate the Vertical RodSystem to the Second Horizontal System

FIGS. 74-79B illustrate embodiments of a second horizontal rod 710 whichcan be used within the dynamic stabilization system 700 described above.Referring now to FIG. 74, the horizontal rod 710 can generally be seenas including a main body 1300 and two cylindrical shafts 1302 extendingaway from each side of the main body 1300. The main body 1300 includescylindrical slots 1304 adjacent to the ends 1306, 1308 of the main body1300 and sockets 1310 for accepting a cam 1312. In this embodiment, thecylindrical slots 1304 are about perpendicular to the cylindrical shafts1302. The two cylindrical shafts 1302 can be connected to the anchorsystem 702 while the cylindrical slots 1304 can be used to accept andsecure the vertical rods 716 to the second horizontal rod 710 as shownin FIG. 48.

Referring now to FIG. 75, the cylindrical slot 1304 for accepting avertical rod 716 and the socket 1310 for accepting a cam 1312 can beseen in greater detail. As shown in FIG. 75, the cylindrical slot 1304is located along the top surface 1314 of the main body 1300 and extendsabout perpendicular to the longitudinal axis of the second horizontalrod 710. In this embodiment, a slit 1316 is located underneath thecylindrical slot 1304 in order to allow the sides of the cylindricalslot 1304 to pinch together around a vertical rod 716 in the deployedconfiguration of the second horizontal rod 710.

Located adjacent to the cylindrical slot 1304 is the socket 1310 foraccepting a cam 1312. One purpose of the cam 1312 is to provide amechanical means to pinch the sides of the cylindrical slot 1304together in order to secure the vertical rods 716 to the secondhorizontal rod 710. The socket 1310 of this embodiment includes a flatfront face 1318, a rounded back face 1320, and two rounded side faces1322, 1324. The front face 1318 includes a groove 1328 while the backface 1320 includes a channel 1326, both of which can be used to helpkeep the cam 1312 secured within the second horizontal rod 710. Thefront and back faces 1318, 1320 are also elevated from the side faces1322, 1324. In this configuration, a cam 1312 having a first side tab1330 and a second side tab 1332 (as shown in FIGS. 77A, 77B) can beinserted into the socket 1310 wherein the side tabs 1330, 1332 areinitially placed adjacent to the side faces 1322, 1324 of the secondhorizontal rod 710. As a vertical rod 716 is placed within thecylindrical slot 1304, the cam 1312 can be twisted in order to positiona first side tab 1332 within the groove 1328 of the front face 1318 anda second side tab 1330 within the channel 1326 of the back face 1320. Inthis configuration, the first side tab 1332 and the second side tab 1334of the cam 1312 secure the cam 1312 to the second horizontal rod 710while also causing the sides of the cylindrical slot 1304 to pinchtogether, thereby securing the vertical rod 716 to the second horizontalrod 710. In an embodiment, the cam 1312 can also include a tapered ridge1334 (as shown in FIGS. 77A, 77B) which further helps to pinch the sidesof the cylindrical slot 1204 together around the vertical rod 716.

Referring now to FIG. 76, the socket 1310 can also include an aperture1340, the aperture 1340 extending from the floor 1336 of the socket 1310to the bottom surface 1342 of the second horizontal rod 710. Theaperture 1340 can include a first section 1344 and a second section1346. In this embodiment, the diameter of the first section 1344 of theaperture 1340 is smaller than the diameter of the second section 1346 ofthe aperture 1340. The height and diameter of the first section 1344 ofthe aperture 1340 can be designed to conform to the shape of a fastenerlocated on the bottom of a cam which can be inserted therein. Forexample, the cam 1312 shown in FIG. 77A includes fasteners 1348 locatedon the bottom of the cam 1312. The cam fasteners 1348 include ends 1350which extend away from the main body 1352 of the fasteners 1348. In use,as the fasteners 1348 are inserted into the aperture 1340 of the socket1310, the fasteners 1348 pinch in until the ends 1350 of the fasteners1348 extend past the first section 1344 of the aperture 1340. Once theends 1350 of the fasteners 1348 extend past the first section 1344 ofthe aperture 1340, the fasteners 1348 return to their relaxedconfigurations, and engage lip 1347, wherein the main body 1352 of thefasteners 1348 engage the second horizontal rod 710 along the firstsection 1344 of the aperture 1340 while the ends 1350 of the fasteners1348 and engage lip 1347 help prevent the cam 1312 from becomingdisengaged from the second horizontal rod 710.

FIGS. 78-79C illustrate an alternative embodiment of a cam 1354.Referring now to FIG. 78, the cam 1354 of this embodiment can be seen asincluding a top section 1356, a cylindrical body 1358 and fasteners 1360on the bottom of the cam 1354. The top section 1356 further includes arestraining tab 1362 and a side tab 1364 located between two grooves1366, 1368. FIG. 79A illustrates cam 1354 which has been force fit inthe socket 1310 of the second horizontal rod 710 in its undeployedconfiguration. The cam 1354 is secured to the second horizontal rod 710through the use of the fasteners 1360 in the same manner as set forthabove for cam 1312. FIG. 79B illustrates cam 1354 within the secondhorizontal rod 710 in its deployed configuration. In this configuration,once the vertical rod 716 is placed in the cylindrical slot 1304 of thesecond horizontal rod 710, the cam 1354 can be rotated until the sidetab 1364 of the cam 1354 is aligned with the groove 1328 of the frontface 1318 of the socket 1310 and the restraining tab 1362 of the cam1354 is placed within an indentation 1370 of the front face 1318 of thesocket 1310. The side tab 1362 causes the sides of the cylindrical slot1304 to pinch together, thereby securing the vertical rod 716 to thesecond horizontal rod 710.

FIGS. 80-85 illustrate an alternative embodiment of the secondhorizontal rod which can be used within the dynamic stabilization system700 described above. Referring now to FIG. 80, a second horizontal rod1400 (previously shown in FIG. 74 as second horizontal rod 710) includesa connector 1402 to secure the second horizontal rod 1400 to thevertical rod 716. The connector 1402 of this embodiment includes a mainbody 1404 and a rotating link 1406. FIGS. 81 and 82 illustrate theindividual components included in this embodiment of the secondhorizontal rod 1400 as well as the connector 1402.

Referring now to FIG. 81, the main body 1404 of the connector 1402 canbe seen as including a C-shaped slot 1408 for housing the rotating link1406 along the front face 1410 of the main body 1404. The main body 1404also includes a first aperture 1412 and a second aperture 1416. Thefirst aperture 1412 is located along the back face 1414 of the main body1404 and is configured to accept the vertical rod 716. The secondaperture 1416 is located at the top 1418 of the main body 1404 and canbe threaded to accept a threaded fastening or set screw 1420.

Referring now to FIG. 83, the rotating link 1406 can be seen asincluding a saddle-shaped groove 1422 on the top surface of the rotatinglink 1446 which is positioned substantially perpendicular to thelongitudinal axis of the rotating link 1406. The saddle-shaped groove1422 includes an aperture 1426 that extends from the top 1424 to thebottom surface 1428 of the rotating link 1406. Finally, the rotatinglink 1406 includes an internal cylindrical bore 1430 for accepting thesecond horizontal rod 1400 which is positioned substantially parallel tothe longitudinal axis of the rotating link 1406.

Referring back to FIG. 80, this embodiment of the second horizontal rod1400 can be seen in its deployed configuration. In this configuration,the second horizontal rod 1400 is inserted into the cylindrical bore1430 of the rotating link 1306. In this embodiment, the secondhorizontal rod 1400 can include a dowel pin 1432 (as shown in FIG. 82)that extends through the aperture 1426 along the bottom surface 1428 ofthe rotating link 1406 (as shown in FIG. 83) when the second horizontalrod 1400 is inserted into the rotating link 1406. One purpose of thedowel pin 1432 is to keep the rotating link 1306 positioned on the rod1400 with restricted motion longitudinally along the rod 1400 andcircumferential about the rod 1400 as will be described in greaterdetail below. It can further be seen in FIG. 80 that the rotating link1406 is placed within the C-shaped slot 1408 of the main body 1404, withthe vertical rod 716 being positioned within the saddle-shaped groove1422 of the rotating link 1406. In this embodiment, the vertical rod 716can be inserted into the aperture 1412 located along the back face 1414of the main body 1404 perpendicular to the second horizontal rod 1400and the rotating link 1406. The extent that the vertical rod 716 isinserted into the aperture 1412 can be varied to accommodate thespecific vertebrae being affected. The fastening screw 1420 is used tosecure the vertical rod 716 and the rotating link 1406 to the main body1404.

As shown in FIGS. 82, 84 and 85, the second horizontal rod 1400 can alsoinclude a section 1434 having threads or grooves 1438 to engage threadsor grooves 1436 on a vertical rod 716. In this embodiment, the threadsor grooves 1438 on the section 1434 engage a recessed, threaded orgrooved section 1436 of the vertical rod 716 on one side of the section1434, while a dowel pin 1432 extends on the opposing side, the dowel pin1432 extending past the aperture 1426 along the bottom surface 1428 ofthe rotating link 1406. In this configuration, the vertical rod 716 isallowed to have limited vertical movement within the main body 1404 ofthe connector 1402. The dowel pin 1432 extends through the aperture 1426of the rotating link 1406, thereby limiting the degrees of freedom ofmotion and with the help of set screw 1420, fix the position of thehorizontal rod 1400 relative to the vertical rod 716. An alternativeembodiment of the connector can eliminate one or any combination of twoor more of the rotating link 1406, the dowel pin 1432, the threads orgrooves 1438, and the threaded or grooved section 1436. It is noted thatthe second horizontal rod 1400 can be a straight rod having a constantdiameter (as shown in FIG. 84) which is made of a stiff and rigidmaterial (titanium, for example). It is also noted that other types ofconnectors can also be used which would be obvious to one skilled in theart without deviating from the scope of the invention.

Method of Implantation and Revised Implantation:

A method of implantation of the system in the spine of the human patientis as follows. First the vertebral levels that are to receive the systemare identified. Then the anchor systems are implanted, generally twoanchor systems for each level. The anchor systems can be implanted usinga cannula and under guidance imaging such as x-ray imaging.Alternatively, the anchor system can be implanted using traditionalspinal surgery techniques. Then the horizontal rods are inserted andsecured to the anchor systems. The horizontal rods can be insertedlaterally through a cannula or with an incision and the use of, forexample, a lead-in cone. Alternatively, the horizontal rods can beinserted using traditional techniques when the anchor systems areimplanted. Thereafter, the vertical rods can be connected to or pivoted,rotated or placed into communication with and secured to the appropriatehorizontal rod.

Should a dynamic stabilization system such as system 100 be initiallyimplanted and then should there be a desire to make the system morerigid or to accomplish a fusion, the system 100 can be revised byremoving the horizontal rod 104 that includes the deflection rods orloading rods and replace it with a horizontal rod 106 which has thevertical rod mounts (FIG. 34) and is thus substantially more rigid. Thusa revision to a fusion configuration can be accomplished with minimaltrauma to the bone and tissue structures of the spine.

Materials of Embodiments of the Invention

In addition to Nitinol or nickel-titanium (NiTi) other super elasticmaterials include copper-zinc-aluminum and copper-aluminum-nickel.However for biocompatibility the nickel-titanium is the preferredmaterial.

As desired, the implant can be made of titanium or stainless steel.Other suitable material includes by way of example onlypolyetheretherketone (PEEK), polyetherketoneketone (PEKK),polyetherketone (PEK), polyetherketoneetherketoneketone (PEKEKK), andpolyetheretherketoneketone (PEEKK). Still, more specifically, thematerial can be PEEK 450G, which is an unfilled PEEK approved formedical implantation available from Victrex of Lancashire, GreatBritain. (Victrex is located at www.matweb.com or see Boedekerwww.boedeker.com). Other sources of this material include Gharda locatedin Panoli, India (www.ghardapolymers.com).

As will be appreciated by those of skill in the art, other suitablesimilarly biocompatible thermoplastic or thermoplastic polycondensatematerials that resist fatigue, have good memory, are flexible, and/ordeflectable have very low moisture absorption, and good wear and/orabrasion resistance, can be used without departing from the scope of theinvention.

Reference to appropriate polymers that can be used in the spacer can bemade to the following documents. These documents include: PCTPublication WO 02/02158 A1, dated Jan. 10, 2002, entitled“Bio-Compatible Polymeric Materials;” PCT Publication WO 02/00275 A1,dated Jan. 3, 2002, entitled “Bio-Compatible Polymeric Materials;” andPCT Publication WO 02/00270 A1, dated Jan. 3, 2002, entitled“Bio-Compatible Polymeric Materials.”

The foregoing description of preferred embodiments of the presentinvention has been provided for the purposes of illustration anddescription. It is not intended to be exhaustive or to limit theinvention to the precise forms disclosed. Many embodiments were chosenand described in order to best explain the principles of the inventionand its practical application, thereby enabling others skilled in theart to understand the invention for various embodiments and with variousmodifications that are suited to the particular use contemplated. It isintended that the scope of the invention be defined by the claims andtheir equivalents.

1. A deflection rod system that can be used with a bone implant systemcomprising: a first rod with first, wherein said first end adapted to besecured to a bone implant system; a mount extending from said first rod;a deflection rod to said mount; wherein said deflection rod is comprisedof an inner, an outer shell, said inner having ends and said outerhaving ends; wherein the inner is comprised of a super elastic materialand the outer shell comprised of a biocompatible material, and whereinthe outer shell is less elastic than the inner; and wherein the inner isinserted into the outer shell so that the ends of the inner extend endsof the outer shell.
 2. The system of claim 1 wherein the inner rod ofthe deflection rod is made of a nickel titanium alloy.
 3. The system ofclaim 1 wherein the outer shell of the deflection rod is made of PEEK.4. The system of claim 1 wherein the inner rod of the deflection rod hasa constant diameter and the outer shell of the deflection rod is taperedfrom said mount to the ends of the outer shell.
 5. The system of claim 1including an end cap mounted at the end of the inner rod, wherein saidend cap is spherically-shaped.
 6. The system of claim 1 including an endcap mounted at the end of the inner rod, wherein said end cap isspool-shaped.
 7. A deflection rod system that can be used with a boneimplant system comprising: a first horizontal rod with at least a firstend, wherein said first end is adapted to be secured to a bone implant;a mount extending from said first horizontal rod; a deflection rodconnected to said mount, the deflection rod having an end; at least onevertical rod, having a first end and a second end; wherein the first endof the at least one vertical rod is connected to the end of thedeflection rod; and a second horizontal rod with a first end, whereinsaid first end of said second horizontal rod is adapted to be secured toa bone implant, wherein the at least one vertical rod is connected tothe second horizontal rod.
 8. The system of claim 7 wherein saiddeflection rod includes at least one spherically-shaped end cap, the atleast one spherically-shaped end cap being rotatably engaged by aconnector and said vertical end is said connector.
 9. The system ofclaim 7, comprising: the deflection rod including at least onespool-shaped end cap; wherein the least one spool-shaped end cap isrotatably engaged by a connector and said vertical rod is saidconnector.
 10. The system of claim 7 wherein the at least one verticalrod is pivotally engaged by a connector which connector is connected tosaid deflection rod.
 11. The system of claim 7, comprising: thedeflection rod including an end cap; a connector including an engagingelement; wherein said engaging element can be positioned to secure theend cap of the deflection rod to the vertical rod with the connector.12. The system of claim 11 wherein the at least one vertical rod ispivotal relative to said deflection rod.
 13. The system of claim 7wherein the first horizontal rod includes deflection restraining ring,said deflection rod being contained within the deflection restrainingring.
 14. The system of claim 7 including a deflection rod shield thatsurrounds the deflection rod.
 15. The system of claim 7, comprising: thesecond horizontal rod including cylindrical slot that accepts the atleast one vertical rod and a socket that accepts a cam; and wherein saidcam causes the cylindrical slot to be urged against the at least onevertical rod, thereby securing the at least one vertical rod to thesecond horizontal rod.
 16. The system of claim 7 comprising a secondconnector to attach the at least one vertical rod to the secondhorizontal rod.
 17. The system of claim 16, further comprising: saidsecond connector includes a main body and a rotating link; said mainbody including an aperture that accepts the at least one vertical rodand a slot that accepts the rotating link; said rotating link includinga saddle-shaped groove on a surface of the rotating link to engage theat least one vertical rod, wherein the at least one vertical rod ispositioned perpendicular to the longitudinal axis of the rotating link;and said rotating link further including an internal cylindrical borethat accepts the second horizontal rod, wherein the second horizontalrod is positioned parallel to the longitudinal axis of the rotating linkwithin the internal cylindrical bore.
 18. The system of claim 1, furthercomprising: wherein the second horizontal rod includes a grooved sectionto engage a grooved section of the at least one vertical rod.
 19. Thesystem of claim 1 including a deflection rod shield that surrounds thedeflection rod.
 20. The system of claim 1 including an end cap connectedto the end of the inner rod.
 21. The system of claim 7 wherein saidmount extends from said first horizontal rod at a location that isdistal from where said first end is secured to a bone implant.